Herbivorous fish names. Abstract: Design of a fish hatchery on the river

Herbivorous fish.

In the CIS, as in many other countries of the world, Far Eastern herbivorous fish belonging to the carp family are used in pond fish farming:

Common, or white, silver carp Hypophthalmichtys molitrix (Val.) (Fig. 42, a). This is a large schooling pelagic freshwater fish, the length of which reaches 1 m, weight -16 kg. Natural distribution area (area) - rivers of East Asia; in Russia - Amur. Acclimatized in some southern rivers of the CIS. The body is tall, covered with small silvery scales. The head is wide, the eyes are below the midline of the body. The fused gill rakers form a filter. The ventral surface has a keel starting from the throat; the intestine is 10 or more times longer than the body. In the Amur it reaches sexual maturity in the 5th-6th year, spawning occurs during the summer flood at a water temperature above 20°C; bighead carp Aristichthys nobilis (Rich.) - close to white, but more heat-loving, from the rivers of Central and Southern China, distinguished by a darker body color and the absence of a keel on the throat (see Fig. 42, b);
grass carp Ctenopharyngodon idella (Val.) is a large freshwater fish that inhabits the same reservoirs as silver carp. It matures in the 7-8th year of life with a length of 65-70 cm. The body is low, elongated, covered with large scales, reaching a length of 122 cm and a weight of 32 kg.
All herbivorous fish are fast-growing, but more thermophilic than carp. Therefore, they are most effective in polyculture of reservoirs in the southern fish farming zones.
Grass carp feeds on higher aquatic vegetation. It is capable of very quickly destroying its own food supply (especially in the southern regions). If there is a lack of vegetation, it easily switches to feeding on compound feed, which can lead to competition with carp. When reared together, grass carp have the same growth rate as bighead carp. It is advisable to use it in pond farming as a biological ameliorator.
Silver carp feeds on microscopic algae - phytoplankton, as well as detritus. There is practically no competition in nutrition with carp and other species in polyculture. When silver carp and carp are reared together, their mutual positive influence on each other can be observed.

Bighead carp is conventionally called a herbivorous fish. Along with zooplankton and detritus, it consumes phytoplankton. With a significant increase in stocking density, it can compete with carp fingerlings in feeding on zooplankton. In the middle zone it grows better than silver carp. In the southern regions of the CIS countries, with a good supply of food, carp grows faster. Herbivorous fish can be grown in lakes, reservoirs and other non-drainage bodies of water (Table 69). For organizing feeding farms on the basis of reservoirs, the most promising are silver carp and its hybrids with bighead carp.

Table 69. Average productivity values ​​of herbivorous fish in various fish-breeding areas of the CIS countries, c/ha

Growing producers. The North Caucasus, southern Ukraine, Moldova, the states of Transcaucasia and Central Asia are most favorable for growing producers of herbivorous fish. In the middle zone, it is advisable to use the warm waters of state district power plants.
Breeders of carp and silver carp can be raised in specialized zonal farms at reproductive complexes. Fish breeding material can be grown in ordinary carp ponds. Joint rearing of fish of the same species, but of different ages, is not recommended [Vinogradov, Erokhina, 1976].
Repair and producers of white and bighead carp can be grown together with carp breeding material. The standards for planting carp in this case apply the same as when growing it in a monoculture. Grass carp can be grown in the same ponds with carp (without feed additives).
In addition to the usual ponds necessary for growing and maintaining breeding material (fry, nursery, feeding, wintering, uterine, quarantine), the reproductive complex includes:
a workshop for incubating eggs and keeping larvae, which is equipped with VNIIPRH incubation devices with a capacity of 200 liters and IVO-2 devices for keeping larvae. The workshop is supplied with water from a settling pond, which provides water with a temperature of more than 18° C during the spawning period. For a successful spawning campaign, it is necessary to have replaceable equipment used for incubating carp and other fish eggs;
earthen cages for keeping breeders after injection, each with an area of ​​30-50 m2;
ponds for pre-spawning maintenance of spawners with an area of ​​0.1-0.2 hectares each.
Female silver carp mature in the southern zones, as a rule, at the age of 3-4 years, bighead carp - 4-5, grass carp - 4 years (Table 70). Males reach sexual maturity much earlier than females. When creating replacement-tagging herds, the use of females maturing for the first time, as well as sires older than 10-12 years, should be avoided.
The requirements for the basic parameters of the hydrochemical regime of ponds when growing herbivorous fish are the same as when growing carp.
In ponds where repairs are grown and spawners are kept, it is necessary to create a sustainable food supply.

Table 70. Working fertility of female herbivorous fish (numerator - absolute, thousand pieces per female; denominator - relative, thousand pieces/kg)

Age, years	Silver carp	Bighead carp	White amur
3	167/83,5	-	-
4	332/107	293/52,9	302/63
5	486/105,6	620/73	434/81,9
6	488/108,4	780/70,3	560/85
7	805/146,4	730/70,2	561/76,7
8	546/85,4	605/46,1	911/95,5
9	631/101,2	850/56,6	834/72,5
10	566/77,6	900/50,3	646/61
11	744/106.3	796/67,4	916/91,6
12	1000/133	840/68,3	740/75,4
13	912/84,4	1244/65,1	700/70
14	786/68,3	903/45,8	720/66,7
15	103/90	1000/48,5	775/63

During periods when there is a lack of aquatic vegetation in ponds, grass carp (especially older age groups) should be fed with terrestrial vegetation (alfalfa, clover, corn, forbs, etc.), their feed coefficient is taken to be 30.
During autumn fishing and when transferring fish for wintering, the number of fish is taken into account, the piece weight and growth are determined, and sick, deformed and injured individuals are discarded. Wintering is carried out in ordinary carp wintering ponds. Ponds of other categories can also be used, where favorable conditions can be provided. The density of planting of breeding herbivorous fish in wintering ponds is as follows: for fingerlings - up to 200-300 thousand fish/ha; for two-year-olds - 200 c/ha; for older breeding material -150 c/ha, for producers -100 c/ha.
If carp are bred on a farm along with herbivorous fish, it is more convenient to winter them separately or with a predominance of herbivorous fish in the planting. The yield standards for various age groups of herbivorous fish during the wintering period are the same as for carp. Wintering ponds are designed to keep breeders separate.
When feeding grass carp with terrestrial vegetation, its production can be increased by 2-3 c/ha.

Standards for growing repairs and producers of herbivorous fish

Ratio of sires, females: males	2:1
Manufacturers reserve, %	100
Average duration of use of manufacturers, years	4
Working fertility of females, thousand pieces. eggs	500
Number of larvae per female, thousand pieces.	250
Density of stocking of spawners in pre-spawning ponds, pcs./ha	1000
Age of producers first used for reproduction, years
females	6-5
males	5-4
Survival rate in maintenance ponds, %
fingerlings from larvae	40
fingerlings from grown up to 25 mg larvae	75
yearlings	85
two-year-olds	85
two-year-olds	90
three year olds	90
three-year-olds and older age groups	95
Repair selection, %
yearlings	50
two-year-olds	50
two and three year olds	95
three- and four-year-old females and males	95
four year olds
females	95
males	37-95
five-year-old females and males	95
five year olds
females	75-95
males	37
six year old females	95
six year old females	75
Average weight of fingerlings taken for repair, g
grass carp	80
bighead carp	80
silver carp	40
two-year-olds, kg
grass carp	1,35
bighead carp	1,35
silver carp	0,85
three-year-olds, kg
grass carp	3
bighead carp	3
silver carp	2
four-year-olds, kg
grass carp	5
bighead carp	5
silver carp	3
five-year plan.kg
grass carp	7
bighead carp	7
silver carp	4
six-year-olds.kg
grass carp	9
bighead carp	9
silver carp	5
Density of stocking of replacement stock in summer repair ponds in a polyculture with carp, pcs/ha
larvae
grass carp	3000
bighead carp	9500
silver carp	25500
larvae grown up to 25 mg
grass carp	1700
bighead carp	5000
silver carp	13500
yearlings
grass carp	90
bighead carp	190
silver carp	140
two-year-olds
grass carp	70
bighead carp	100
silver carp	250
three-year-olds
grass carp	50
bighead carp	70
silver carp	190
four-year students
grass carp	50
bighead carp	50
silver carp	180
five year olds
grass carp	50
bighead carp	50
silver carp	170
Planting density of breeders in summer brood ponds in polyculture with carp, pcs/ha
White amur
females	10
males	10
bighead carp
females	30
males	50
silver carp
females	80
males	120
Increase in producers in summer brood ponds, kg/piece
White amur
females	1,5
males	1
bighead carp
females	1,5
males	1
silver carp
females	1,3
males	0,8
Planting Density
fingerlings in winter repair ponds, thousand pcs/ha	200-300
producers in winter ponds for all age groups, pcs/ha	1000
replacement stock in winter ponds for all age groups, except fingerlings, t/ha	10-20

When forming broodstocks of herbivorous fish, it is necessary to use the two-line breeding recommended for carp - the reproduction of two unrelated groups of fish with the selection of females and males of different origins. This allows you to avoid inbreeding and expect rapid growth of hybrids.
The main selection for the broodstock is carried out among first-time maturing sires based on the degree of expression of sexual characteristics. Under favorable housing conditions, at least 80-90% of females and almost all males are selected from the older age group of repairs as spawners.
When determining the size of a farm's broodstock, it is necessary to take into account that, for a number of reasons, some females do not mature after injection or produce eggs that are not entirely of good quality. Therefore, it is necessary to have a reserve of females in the broodstock (at least 50%). There is no need to have a reserve of males, since when producing the offspring of herbivorous fish, artificial insemination of eggs is carried out; fewer males are required than females. For every 5 female silver carp in the broodstock, it is enough to have 3-4 males, and for every 5 female grass carp - 2-3 males.
When grading breeding material of herbivorous fish, the same techniques can be used as when grading breeders and repairing carp. Every year in the spring, when the wintering ponds are unloaded, all fish are inspected, weighed, and the necessary measurements are taken.
Fish from wintering areas are caught by water using a Hamsoros seine. Fish are selected from the seine using fabric sleeves 1-1.3 m long, placed on one side on a metal hoop with a diameter of 30-35 cm. The caught spawners are transferred to stretchers with water, equipped with canvas covers. The length of the stretcher is 1.5 m, the width is 40-45 cm. For weighing, deep stretchers (cradles) are used. Producers are kept in wintering ponds until spawning begins. Carrying out grading of broodstock at an earlier stage is pointless, since before the onset of spawning temperature, producers often do not have well-defined sex differences.
The main sign indicating the readiness of females for spawning is the presence of a convex, pendulous abdomen. This sign is especially clearly expressed in white and bighead carp, and to a lesser extent in grass carp.
A characteristic feature that allows one to distinguish males of herbivorous fish from females (in addition to the secretion of milk) is the presence of peculiar horny denticles - spines - on the rays of the inner side of the pectoral fins. They are most clearly visible in male silver carp - large and sharp (usually on the second and third rays). In bighead carp they are less sharp, in the form of tubercles. Male grass carp have very small spines (most pronounced on the first hard ray), and the upper surface of the pectoral fins feels like sandpaper to the touch.
Spines on the pectoral fins of male silver carp can be found throughout the year. Male grass carp have spines on their pectoral fins only during the feeding period; in the fall, when the temperature drops, they disappear and appear in the spring, after the water warms up. Some female silver carp (especially older ones) also have teeth on their pectoral fins, but they are located much less frequently.
During grading, females are divided into 3 groups:
1. The most mature females. The abdomen is soft to the touch, saggy. Sometimes swelling is noticeable in the area of ​​the genital opening. This group of females is used primarily for work.
2. Females with similar external characteristics, but less pronounced. They can be used later, after finishing work with females of the 1st group.
3. Females are almost no different in appearance from males. They are not used to obtain caviar, but are immediately discarded after grading or planted for summer feeding.
During grading, males are divided into 2 groups:
1. Males give milk easily and have a well-defined nuptial plumage.
2. Males produce very little milk or do not flow. Fish selected for offspring by species, sex and groups are placed in ponds for pre-spawning maintenance. Producers are kept in them until reproductive products are obtained.
For pre-spawning housing, spawners use small, easily fished ponds with an area of ​​0.05-0.2 hectares and a depth of 1.5-2 m. Ponds for pre-spawning housing should be well planned, quickly drained and filled with water (no more than 2-3 hours) , have a constant water exchange to prevent excessive heating of the water. A good oxygen regime is a prerequisite: a drop in oxygen content below 4 mg/l in pre-spawning ponds is unacceptable. Planting producers in ponds up to 1000 pcs/ha, but not more than 10-15 c/ha. Overexposure of mature females in ponds with spawning temperatures leads to the appearance of degenerative changes in the ovaries, that is, to overripeness of the females. Males mature 10-15 days earlier.
During industrial breeding of herbivorous fish, significant post-spawning mortality of spawners, especially silver carp, is observed. It is not uncommon for more than half of the producers to die.
The main reasons causing the death of spawners during the spawning campaign:
1) injuries during fishing, injection and straining of caviar and milt;
2) the use of females that do not respond to pituitary injections to produce offspring.
Incomplete ovulation may be a consequence of an underestimated dosage of the pituitary gland, but there is never a deterioration in the condition of the fish after the first (preliminary) injection. Careful spring grading and carrying out work to obtain offspring of herbivorous fish in a short time make it possible to avoid the use of females that do not mature after pituitary injections and to significantly reduce the death of spawners during the spawning campaign.
To prevent injuries, practice-proven methods are used:
the use of earthen spawning cages with hidden hydraulic structures;
catching fish using special hoses;
use of anesthesia.
Post-injection inflammatory processes in producers of herbivorous fish are relieved with penicillin. Producers weighing from 5 to 12 kg are administered 50 thousand IU per fish.
In Turkmenistan and Uzbekistan, work begins approximately in early May, in the Krasnodar Territory - in the second half of May, in Moldova - in early June, and in the Astrakhan, Volgograd and Rostov regions - in the northernmost disengagement points - in the second half of June.
Prolonged maintenance of spawners at spawning temperatures leads to their overripeness, therefore all work on the reproduction of herbivorous fish should be carried out in a short time - 25-30 days. As a rule, silver carp and grass carp are the first to ripen. After a few days (7-10), depending on the water temperature, they begin working with bighead carp.
The method of factory reproduction of herbivorous fish has almost no significant differences for individual species.
Females with gonads in stage IV of maturity are given a preliminary pituitary injection at the rate of: for each, 3 mg of pituitary dry matter with a weight of 5-7 kg and 5-6 mg for larger ones. A day after the preliminary injection, a permissive injection is made at the rate of 3-6 mg of pituitary dry matter per 1 kg of female weight, depending on the size of the gonads. At the same time, males weighing 5-7 kg are administered 4-6 mg, larger ones - up to 10-12 mg of pituitary dry matter per fish.
Currently, choriogonic gonadotropin and synthetic gonadal otropic hormones are also used to stimulate the maturation of herbivorous fish.
The injection time of the producers is chosen in such a way that, taking into account the water temperature and the rate of maturation of the females, the receipt and insemination of eggs, and their placement in the incubation apparatus, occur during daylight hours. A preliminary injection is carried out, as a rule, at 18-19 hours, allowing - starting from this time and later. However, during sudden cold spells at night, injections are sometimes postponed to the morning. If the average daily water temperature drops below 20° C, work is stopped until warming occurs.
After injection, males and females are planted separately in small injection cages with an area of ​​20-30 m2, equipped with a bottom drainage through a grate and a canvas sleeve on the water supply pipe. Ponds must have constant water exchange; water must be released from them and the cages filled in no more than 30 minutes. Up to 10 breeders are planted in each cage. It is possible to keep the breeders in container baths made of tarpaulin, fiberglass and other materials, while ensuring constant water exchange. The water consumption is 3-4 l/min. During the entire period of reproduction work, water in cages and containers is carefully monitored.
The rate of maturation of females after a permissive injection largely depends on the water temperature

t water/С	20-22,	23-25,	26-28
Ripening time, h	10-12,	9-11,	7-10

After 6-9 hours, they begin to regularly check the state of maturity of females. The interval between checks is determined depending on changes in water temperature during the day, age and condition of the females. But it cannot be more than 1.5-2 hours. This is due to the danger of overripening. For ease of work, it is advisable to sort females of different sizes, origins and degrees of maturity into groups. If the females are heterogeneous, it is necessary to transplant them upon inspection into a free, water-filled cage or container. In this case, all females are examined, since they can mature at different times. Determining the exact time of maturation is very important, but only a specialist with extensive experience in practical work on fish farms can do this skillfully.
Milt is collected in separate test tubes for each male 30-60 minutes before the start of work on obtaining caviar. You can not store milk, but express it directly onto the caviar. It is important to wipe the male's abdomen well so that no water gets into the milk; Store milk in a thermos on ice for 6-12 hours.
The amount of caviar is taken into account by weighing a previously prepared basin with caviar, determining the volume of caviar directly in the basin using calibrated marks or by pouring it into a measuring container, preferably into a nylon or polyethylene mug with divisions. You can express caviar into such a mug when selecting it from a female. 1 g or 1 ml of unfertilized eggs of herbivorous fish contains 800-1000 eggs of grass carp, 900-1200 of white carp and 600-800 of bighead carp.
The fertility of female herbivorous fish varies widely - from several tens of thousands to 2 million. But for fish farming calculations, the working fertility of a repeated spawning female weighing 5-7 kg is taken on average equal to 500 thousand eggs.
Immediately after determining the number of eggs, they are inseminated with sperm from 2-4 males. For 1 liter of caviar, 5 ml of sperm is enough. The milk is carefully spread over the caviar using a bird's feather, a small amount of water is added and the caviar is carefully distributed in it. At this time, fertilization occurs. After 1-2 minutes, add fresh water and drain it, repeating this operation 1-2 more times. You can wash the caviar from mucus, blood, scales, and lumps of caviar for several minutes; placing a hose with low-flowing water on the edge of the basin to prevent the eggs from being carried away. Without waiting for complete swelling, no later than 5-10 minutes after fertilization, the eggs are placed in incubation apparatus.
It is advisable to place the eggs of each female for incubation in a separate apparatus. It swells a lot. The diameter of the unfertilized egg is 1.0-1.2 mm, and after swelling - 5 mm or more.
A standard Weiss incubator with a volume of 8 liters holds only about 50 thousand eggs, so the use of these devices for incubating herbivorous fish is ineffective, given their high fertility. Therefore, devices made from plexiglass of the VNIIPRKh system with a capacity of 50 to 200 liters are used (Table 71).

Table 71. Basic technical data of incubation apparatus for herbivorous fish

When feeding water with high mineralization (1.6-2.0 g/l) into the apparatus, the amount of eggs laid can be increased by 2-2.5 times due to its less swelling.
Before laying the eggs, the water level in the apparatus is reduced by one third, adjusting its supply so that the eggs are in slight movement in the lower part of the apparatus, and the water consumption, after the eggs swell, does not exceed the required value. Water is supplied to the incubation workshop from the settling pond through a filter made of a thick nylon sieve (no. 46 and above). If heating is used, water is supplied to the workshop through a pool, where air bubbles are removed, which can, by attaching to the eggs, carry them out of the apparatus with a current of water.
During incubation, eggs are also released; increasing at water temperatures below 17°C, it is accompanied by an increase in the number of deformities. The quality of eggs and the results of incubation are greatly influenced by the conditions of keeping the spawners during the feeding period and pre-spawning time.
Before the end of incubation, the percentage of malformed embryos and the percentage of free embryos are determined. These indicators can be used when selling larvae to determine their number in each apparatus. Under favorable incubation conditions and good quality reproductive products, the yield of free embryos is at least 70-80% of the amount of laid eggs. If during aging there is a significant loss of larvae, their number is determined again by the standard method.
During the incubation period, water exchange in the apparatus is maintained in such a way that the eggs are not washed out and at the same time, stagnant zones do not form. If there are a large number of dead eggs, they are selected after the end of the gastrulation process, that is, 13 hours after the start of incubation, by suction with a rubber hose, while slowing down the water exchange in the apparatus by half. The duration of incubation depends on the temperature of the water entering the apparatus. At an optimal temperature in the range of 21-25°C, it is 23-33 hours, decreasing to 17-19 hours when the water temperature rises to 27-29°C. This dependence applies to all types of herbivorous fish. Mass hatching of embryos occurs within 1-3 hours, sometimes it lasts up to 12 hours, and sometimes for a day. In these cases, the hatching process is artificially stimulated by reducing the water supply by 3-5 times for several minutes, restoring the flow after hatching occurs in order to avoid freezing.
Soon after hatching, free embryos rise to the upper layers of the water and, together with the current, are carried out of the apparatus through gutters or hoses into the holding apparatus.
Most often, IVA-2 devices are used for keeping larvae.
The rearing of larvae of herbivorous fish in fry ponds is carried out in stages (Table 72).

Table 72. Technological operations for growing larvae of herbivorous fish in fry ponds

Name	Description	lead time
Reclamation works	Clearing and deepening of the drainage network, removal of dry vegetation, liming	-
Application of organic fertilizers	Adding humus or compost to the pond bed (3-5 t/ha)	30 days before pond filling
Filling the pond with water	Water supply through a fish catcher from a nylon sieve N 32 installed on the water supply pipe	In 1-2 days, planting the larvae
Cleaning the fish catcher	Removing the contents of the catcher	Before draining the pond
Planting larvae	Release of larvae into ponds at the stage of mixed feeding after preliminary counting (visually using a standard or volumetric method); before releasing the larvae, the temperature of the water in the transport containers where they are transported is equalized with the temperature of the water in the ponds	-
Application of mineral fertilizers	Application of mineral fertilizers by water at a one-time rate of 30 kg/ha of ammonium nitrate and 15 kg/ha of superphosphate, the total fertilizer consumption is 1.0-1.5 c/ha for the entire period	Weekly
The use of organic fertilizers with poor development of the natural food supply and favorable oxygen conditions in ponds	Application of humus, compost (2-5 c/ha) along the water edge or dried vegetation in the form of sheaves along the coastline (5-10 c/ha)	On the 3-5th day after planting the larvae
Control of predatory aquatic insects	Introduction of high-molecular alcohols into the pond at a single rate of 300-500 g, the total consumption of higher fatty alcohols, depending on wind strength, is -15 kg/ha for the entire period	Every day from the moment the ponds are filled with water until the end of the 3rd growing period
Temperature observations	Measuring water temperature using a water thermometer	Three times a day
Observations of the gas regime	Determination of oxygen dissolved in water using an oximeter or the Winkler method	Every day, at 6 and 16 o'clock
Observations on the development of natural food resources	Sampling of zooplankton using a plankton grid, qualitative and quantitative sample processing, algae development is determined using a Secchi disk, optimal development corresponds to a water transparency of 35-40 cm	Daily
Observations on the growth rate and nutrition of juveniles	Carrying out control catches, selecting 30 specimens. for weighing, measuring and studying nutrition	Once every 10 days of juveniles,
Installation of a fish catcher	The fry catcher is installed in a waterproof box using guy ropes and attached to the drainage pipe using a cuff.	Before catching fry
Descent of ponds	Removing the sand bars, establishing the difference in water horizons in the pond and in the fry catcher is no more than 10 cm	During the period of draining water from ponds
Installing a screen in the "monk" and catching juveniles from the catcher	The grown juveniles from the catcher are caught in leaps and bounds and transferred to a bucket of water, and then to a cage installed on running water.	In the early morning hours and evening
Keeping juveniles in cages before transportation	Keeping in running water	Within 4-6 hours
Counting and transporting juveniles	Counting of juveniles is carried out visually: according to a standard or volumetric method; transportation within the farm is carried out in milk cans, plastic bags and live fish machines.	The duration of on-farm transportation should not exceed 1 hour

Work on raising larvae of herbivorous fish is carried out at water temperatures above 20° C (preferably 23-28° C). Short-term drops in water temperature during the growing period to 16-18°C are acceptable. The optimal content of oxygen dissolved in water is 6-12 mg/l; it is permissible to reduce the oxygen content to 4-5 mg/l.

Technical standards for equipment for raising fry of herbivorous fish

Fry Pond
area, ha	up to 1
average depth, m	1,0-1,5
duration, h
filling the pond	12
draining the pond	24
Tray fish catcher
metal mesh mesh, mm	0,5
nylon sieve	╧ 32
Sleeve made of nylon sieve
length, m	2,5-3
diameter, cm	50
nylon sieve	╧ 32
Fry catcher (wooden box or concrete pool), m
length	3,5-4
width	1,2-1,5
height	0,8-1
water layer height	0,6-0,8
difference in water horizon in a pond and in a filled box, cm	no more than 10
Catcher made of nylon sieve, cm
length is less than the length of the box or pool	by 50
width is less than the width of the box or basin	no more than 15-20
Anti-chip partition (sewn into 1/3 of the catcher’s width)
length shorter than catcher length, cm	at 15-20
material - nylon sieve	╧ 7-12
Cage for keeping grown juveniles before transportation
material - nylon sieve	╧ 7-12
wooden frame, m
length	1
width	1
height	0,45
distance from the bottom of the cage to the bottom of the reservoir, m	not less than 0.4
water flow speed in the area where cages are installed, m/s	0,05-0,2
Net for catching juveniles
diameter, cm	30
depth, cm	30
material - nylon sieve	╧20-23

Biological standards for rearing and transporting juveniles

Planting density of herbivorous fish larvae obtained in a factory way, million pcs/ha	1,5-5
Average weight of fry at the end of growing, mg	20-30
Survival rate of juveniles in fry ponds, %	40-50
Duration of growing, days	10-15
Optimal concentration of zooplankton
in fry ponds, specimens/l	1000-1500
Phytoplankton biomass, mg/l	no more than 30
Permissible concentration of grown juveniles in cages, thousand pieces/cage	no more than 70
Duration of keeping juveniles in cages before transportation, hours	4-6
Norm for placing juveniles in plastic bags or milk cans with a capacity of 40 liters without oxygen (thousand pieces) for transportation duration, hours
up to 4	2
up to 8	1
Norms for placing juveniles in live-fishing machines (tank capacity 3 m3) without aeration for a transportation duration of up to 8 hours, thousand pcs.	100
Norm for placing juveniles in plastic bags with a capacity of 40 liters with oxygen (thousand pieces) during long-term transportation with weight, mg
5-30 17-25
30-50	10-15
Norm for placing juveniles in live-fishing machines (tank capacity 3 m3) with aeration (thousands of pieces) during long-term transportation with a weight of 10-20 mg	18-20

The duration of the larval incubation process depends mainly on the water temperature:

The survival rate (from fertilized eggs to larvae switching to mixed nutrition) should be at least 50%.
For incubation of eggs and maintenance of free embryos of herbivorous fish, universal incubation devices ("Amur", etc.) are used, which makes it possible to simplify the entire technology for producing larvae.
In China, Japan and India, flow-through round and rectangular pools are also used to obtain the caviar of herbivorous fish.
The sum of active temperatures (above 15°C), ensuring the normal functioning of the reproductive system of herbivorous fish, must be above 2600 degree days. The supply of heated water to the ponds increases the duration of the growing period and allows, with the targeted formation of the food supply, to obtain standard fish growth, ensuring the possibility of reproduction in the optimal time frame (end of May - first half of June). Artesian wells can be used to regulate the temperature of the water entering the hatchery. Successful temperature management in ponds is limited to an area of ​​up to 1.5 hectares. In ponds of a larger area, the effect of supplying warm water is sharply reduced. The best shape for ponds is rectangular with a length to width ratio of 2:1 or 3:1. The number of days with a water temperature of 20° C and above must be at least 60. This determines the mode of supply of warm water throughout the year (Table 73).

Table 73. Approximate graph of water consumption in ponds of different categories during the year, l/s/ha

Pond category	Pond area.ha	Spring			Summer			Autumn			Winter
		III	IV	V	VI	VII	VIII	IX	X	XI	XII	I	II
Pre-spawning	0,05-0,1	-	30	40-50	up to 30	-	-	-	-	-	-	-	-
Summer repair	1-1,5	5	25	20	8-12	5	5	up to 20	up to 30	5	2	2	2
Summer-uterine	0,5-1	8-10	30	-	8-12	5	5	up to 20	up to 30	5	2	2	2

The mode of supply of warm water to the ponds is adjusted depending on the temperature of the water in the water supply source and weather conditions.
In female herbivorous fish reared in temperature-controlled ponds, the time to reach puberty is significantly reduced due to a reduction in the duration of stages I and II of ovarian maturity. Females of silver carp and grass carp mature at the age of 4 years, bighead carp - at the 5-6th year of life. Males of all species mature a year earlier.
The normative increase in body weight, starting from the third year of life, should be: at least 0.7-0.8 kg - for silver carp and grass carp; 1 kg - for bighead carp (Table 74).

Table 74. Basic standards for growing breeding material of herbivorous fish in ponds with controlled temperatures

Age, years	Survival rate, %	Silver carp		Bighead carp		White amur
		average weight of fish, g	fish productivity, c/ha	average weight of fish, g	fish productivity, c/ha	average weight of fish, g	fish productivity, c/ha
Fingerlings	60	30(40)	3	60(80)	3	50(60)	1
Two year olds	85	400(500)	1,5	800(1000)	2	500(600)	1
Three year olds	100	1200	1,2	2000	2	1400	0,8
Four year olds	100	2000	1	3500	1,5	2200	0,8
Five-Year Plans	100	2700	1	5000	1,5	3000	0,8
Six-year-olds	-	-	-	6500	1,5	-	-

Producers are released for summer feeding at the rate of: silver carp - 60-80, bighead carp - 50-60, grass carp - 40-50 pcs/ha.
Standard indicators of body weight gain for producers during the summer feeding period should be at least 0.8-1.0 for silver carp and grass carp, and 1.0-1.5 kg for bighead carp.
The density of planting of breeding fingerlings of herbivorous fish in wintering ponds is 200-300 thousand/ha, two-year-olds - up to 200, older ones - 150, producers - no more than 100 c/ha. The standards for the release of herbivorous fish from wintering are the same as for carp. Joint wintering of breeders of herbivorous fish and carp due to different breeding periods is not allowed. When forming broodstocks, the needs of farms for planting material of various types of herbivorous fish should be taken into account (Table 75).

Table 75. Productivity indicators of female herbivorous fish

When organizing the artificial reproduction of herbivorous fish under warm-water conditions, the same technological techniques are used as in conventional reproduction complexes.
Growing fingerlings of herbivorous fish. It is carried out together with carp fingerlings. This greatly simplifies the task of creating a sustainable food supply for them.
Small (up to 10 ha), well-planned nursery ponds are used to raise young of the year herbivorous fish. Water supply to these ponds must be carried out through litter traps with a mesh having a mesh of no more than 1 mm.
It is advisable to plant ungrown larvae in ponds soon after filling them with water (no later than 7-10 days). Immediately after delivery to the fish farm, packages with larvae are placed in ponds to equalize the temperature (for about 30 minutes), then the packages are opened, pond water is added to them, after which the larvae are carefully released into the reservoir.
Stocking of nursery ponds with fry raised in fry ponds is carried out using mesh cages measuring 160x75x60 cm, the end walls and bottom are canvas. These cages are installed in pairs in a canvas vat in the back of a car. In one trip, a truck equipped with these cages transports 100-150 thousand. fry depending on ~ their average weight. Under satisfactory growing conditions, the yield from larvae that have switched to a mixed diet and fingerlings should be no lower than 40% in fish farms located in the southern regions of the CIS, and no lower than 30% in fish farms in the middle zone. When stocking nursery ponds with grown juveniles, the yield of fingerlings in the southern zones is planned to be no lower than 70%, in the middle zone - 50%.
When growing herbivorous fish and carp in a polyculture, the natural food supply of ponds is used extremely fully, which makes it possible to significantly increase the productivity of ponds without the additional cost of granulated feed. Forward

Predators of the underwater world include fish, whose diet includes other inhabitants of water bodies, as well as birds and some animals. The world of predatory fish is diverse: from terrifying specimens to attractive aquarium specimens. What they have in common is the possession of a large mouth with sharp teeth for catching prey.

A feature of predators is unbridled greed, excessive gluttony. Ichthyologists note the special intelligence of these creatures of nature and ingenuity. The struggle for survival contributed to the development of abilities that predatory fish superior even to cats and dogs.

Marine predatory fish

The vast majority of marine fish of predatory families live in tropical and subtropical zones. This is explained by the presence in these climatic zones of a huge variety of herbivorous fish and warm-blooded mammals that make up the diet of predators.

Shark

Unconditional leadership takes white predatory fish shark, the most insidious for humans. The length of its carcass is 11 m. Its relatives of 250 species also pose a potential danger, although attacks by 29 representatives of their families have been officially recorded. The safest is the shark - a giant, up to 15 m long, feeding on plankton.

Other species, larger than 1.5-2 meters, are insidious and dangerous. Among them:

• Tiger shark;
• hammerhead shark (large outgrowths with eyes on the sides of the head);
• mako shark;
• katran (sea dog);
• gray shark;
• spotted shark scyllium.

In addition to sharp teeth, fish are equipped with prickly spines and hard skin. Cuts and blows are no less dangerous than bites. Wounds inflicted by large sharks are fatal in 80% of cases. The jaw strength of predators reaches 18 tf. With its bites it can dismember a person into pieces.

Pictured is a rockfish

Scorpena (Sea Ruff)

Predatory bottom fish. The body, compressed on the sides, is variegatedly colored and protected by spines and shoots for camouflage. A real monster with bulging eyes and thick lips. It lives in the thickets of the coastal zone, no deeper than 40 meters, and winters at great depths.

It is very difficult to notice it at the bottom. The food supply includes crustaceans, greenfinches, and silversides. Doesn't rush after prey. He waits for her to come closer, then he throws him into his mouth. It lives in the waters of the Black and Azov Seas, the Pacific and Atlantic Oceans.

Oshiben (galeya)

A medium-sized fish, 25-40 cm long, with an oblong body of a dirty color and very small scales. A bottom predator that spends time in the sand during the day and goes out hunting at night. The food contains mollusks, worms, crustaceans, small fish. Features include pelvic fins on the chin and a special swim bladder.

Atlantic cod

Large individuals up to 1-1.5 m long, weighing 50-70 kg. It lives in the temperate zone and forms a number of subspecies. The color is green with an olive tint, with brown inclusions. The basis of nutrition is herring, capelin, cod, and mollusks.

They feed their own young and small relatives. Atlantic cod are characterized by seasonal migrations over long distances of up to 1.5 thousand km. A number of subspecies have adapted to live in desalinated seas.

Pacific cod

It is distinguished by a massive head shape. The average length does not exceed 90 cm, weight 25 kg. Lives in the northern zones of the Pacific Ocean. The diet includes pollock, shrimp, and octopus. A sedentary stay in a body of water is typical.

Catfish

Marine representative of the genus Perciformes. The name was received for the front teeth, similar to those of a dog, fangs protruding from the mouth. The body is eel-shaped, up to 125 cm long, weighing on average 18-20 kg.

It lives in moderately cold waters, near rocky soils, where its food supply is located. In behavior, the fish is aggressive even towards its relatives. The diet includes jellyfish, crustaceans, small fish, and shellfish.

Pink salmon

A representative of small salmon, with an average length of 70 cm. The habitat of pink salmon is extensive: the northern regions of the Pacific Ocean, entering the Arctic Ocean. Pink salmon are a representative of anadromous fish that migrate to fresh waters to spawn. Therefore, small salmon are known in all the rivers of the Northern, on the Asian mainland, Sakhalin and other places.

The fish got its name from its dorsal hump. Characteristic dark stripes appear on the body before spawning. The diet is based on crustaceans, small fish, and fry.

Eel-pout

An unusual inhabitant of the coasts of the Baltic, White and Barents seas. A bottom-dwelling fish whose preferences are sand overgrown with algae. Very tenacious. It can wait among the wet stones for the tide or hide in a hole.

The appearance resembles a small animal, up to 35 cm in size. Large head, body tapers to a sharp tail. The eyes are large and protruding. The pectoral fins look like two fans. Scales like those of a lizard, but do not overlap the next one. The eelpout feeds on small fish, gastropods, worms, and larvae.

Brown (eight-lined) greenling

Found near rocky headlands on the Pacific coast. The name refers to the color with green and brown shades. Another option was obtained for a complex drawing. The meat is green. The diet, like many predators, includes crustaceans. There are many relatives in the greenling family:

• Japanese;
• Steller's greenling (spotted);
• red;
• single-line;
• single-feathered;
• long-browed and others.

Names of predatory fish often convey their external features.

Gloss

Found in warm coastal waters. The length of the flat fish is 15-20 cm. In appearance, the glossa is compared to river flounder; it is adapted to live in water of varying salinity. It feeds on bottom food - mollusks, worms, crustaceans.

Glossa fish

Beluga

Among predators, this fish is one of the largest relatives. The species is listed in Krasnaya. The peculiarity of the structure of the skeleton is the elastic cartilaginous chord and the absence of vertebrae. The size reaches 4 meters and weight – from 70 kg to 1 ton.

It is found in the Caspian and Black Seas, and during spawning in large rivers. The characteristic wide mouth, overhanging thick lip, and 4 large antennae are characteristic of the beluga. The uniqueness of the fish lies in its longevity; its age can reach a century.

Eats fish. Under natural conditions, it forms hybrid varieties with sturgeon, stellate sturgeon, and sterlet.

Sturgeon

Large predator, up to 6 meters long. The average weight of commercial fish is 13-16 kg, although giants reach 700-800 kg. The body is highly elongated, without scales, covered with rows of bony scutes.

The head is small, the mouth is located below. It feeds on bottom organisms and fish, providing itself with 85% protein food. Tolerates low temperatures and periods of lack of food well. Lives in salt and freshwater bodies of water.

Stellate sturgeon

The characteristic appearance is due to the elongated shape of the nose, the length of which reaches 60% of the length of the head. Stellar sturgeon is inferior in size to other sturgeons - the average weight of the fish is only 7-10 kg, length 130-150 cm. Like its relatives, it is a long-liver among fish, living 35-40 years.

Lives in the Caspian and Azov seas with migration to large rivers. The basis of nutrition is crustaceans and worms.

Flounder

The sea predator is easy to distinguish by its flat body, eyes located on one side, and a circular fin. She has almost forty varieties:

• star-shaped;
• yellowfin;
• halibut-shaped;
• proboscis;
• linear;
• long-snouted, etc.

Distributed from the Arctic Circle to Japan. Adapted to live on muddy bottoms. Hunts from ambush for crustaceans, shrimp, and small fish. The sighted side is characterized by mimicry. But if you startle it, it abruptly breaks away from the bottom, swims to a safe place and lies on the blind side.

Lichia

A large sea predator from the horse mackerel family. Found in the Black and Mediterranean Seas, the eastern Atlantic, and the southwestern Indian Ocean. Grows up to 2 meters with a weight gain of up to 50 kg. Lihi's prey includes herring, sardines in the water column and crustaceans in the bottom layers.

Whiting

A predatory schooling fish with a runaway body. The color is gray, with a purple tint on the back. Found in the Kerch Strait, the Black Sea. Loves cold waters. By the movement of anchovy, you can monitor the appearance of whiting.

Whip

Inhabits the coastal waters of the Azov and Black Seas. Up to 40 cm long and weighing up to 600 g. The body is flattened, often covered with spots. Open gills increase the size of the deprived head and frighten predators. Among rocky and sandy soils it hunts with shrimps, mussels, and small fish.

River predatory fish

Freshwater predators are well known to fishermen. This is not only a commercial river catch, known to cooks and housewives. The role of insatiable inhabitants of reservoirs is to eat low-value weeds and diseased individuals. Predatory freshwater fish carry out a kind of sanitary cleaning of reservoirs.

Chub

A picturesque inhabitant of Central Russian reservoirs. Dark green back, golden sides, dark border along the scales, orange fins. Loves to eat fish fry, larvae, and crustaceans.

Asp

The fish is called a horse for its quick jumping out of the water and deafening falls on its prey. The blows with the tail and body are so strong that small fish become stiff. The fishermen nicknamed the predator the river corsair. Keeps to himself. The main prey is bleak floating on the surface of reservoirs. Lives in large reservoirs, rivers, and southern seas.

Som

The largest predator without scales, reaching a length of 5 meters and a weight of 400 kg. Favorite habitats are the waters of the European part of Russia. The main food of catfish is shellfish, fish, small freshwater inhabitants and birds. It hunts at night and spends the day in holes and under snags. Catching a catfish is a difficult task, as the predator is strong and smart

Pike

A real predator in habits. It attacks everything, even its relatives. But it gives preference to roach, crucian carp, and rudd. Does not like prickly ruff and perch. It catches and waits until the prey calms down before swallowing.

Hunts frogs, birds, mice. It is distinguished by fast growth and good camouflage. It grows on average up to 1.5 meters and weighs up to 35 kg. Sometimes there are giants as tall as human beings.

Zander

Large predator of large and clean rivers. The weight of a meter-long fish reaches 10-15 kg, sometimes more. Found in sea waters. Unlike other predators, the mouth and throat are small, so small fish serve as food. Avoids thickets so as not to become prey for pike. Active in hunting.

Predatory fish pike perch

Burbot

Belonesox

Small predators are not afraid to attack even comparable fish, which is why they are called miniature pikes. Gray-brown color with black spots like a line. The diet includes live food from small fish. If the whitefish is well-fed, then the prey will be alive until the next lunch.

Tiger perch

A large fish with a contrasting color, up to 50 cm long. The body shape resembles an arrowhead. The fin on the back extends to the tail, with which it provides acceleration in pursuit of prey. The color is yellow with black stripes along the diagonal. The diet should include bloodworms, shrimp, and earthworms.

Livingston cichlid

Video of predatory fish reflect the unique mechanism of ambush hunting. They occupy the position of a dead fish and withstand a sudden attack of emerging prey for a long time.

The length of the cichlid is up to 25 cm, the spotted color varies in yellow-blue-silver tones. A red-orange border runs along the edge of the fins. The food in the aquarium is pieces of shrimp, fish, etc. Don't overfeed.

Toadfish

The appearance is unusual; the huge head and growths on the body are surprising. Thanks to camouflage, the bottom dweller hides among snags and roots, waiting for the victim to approach to attack. In the aquarium it feeds on bloodworms, shrimp, pollock or other fish. Loves solo content.

Leaf fish

A unique adaptation to a fallen leaf. Camouflage helps to guard prey. The size of the individual does not exceed 10 cm. The yellowish-brown color helps to imitate the drifting of a fallen tree leaf. The daily diet includes 1-2 fish.

Biara

Suitable for keeping in large aquariums only. The length of individuals is up to 80 cm. The species is a real predator with a large head and a mouth full of sharp teeth. Large fins on the abdomen look like wings. It feeds only on live fish.

Tetra vampire

In an aquarium environment it grows up to 30 cm, in nature – up to 45 cm. The ventral fins look like wings. They help make quick dashes for prey. When swimming, the head is down. Live fish may be abandoned in the diet in favor of pieces of meat and mussels.

Aravana

A representative of the oldest fish up to 80 cm in size. An elongated body with fins forming a fan. This structure gives acceleration in hunting and the ability to jump. The structure of the mouth allows it to grab prey from the surface of the water. You can feed shrimp, fish, and worms in the aquarium.

Trahira (Tertha-wolf)

Amazon Legend. Aquarium maintenance is available to experienced specialists. Grows up to half a meter. Gray powerful body with a large head and sharp teeth. Fish feed not only on live food, but also serve as a kind of orderly. In an artificial reservoir it feeds on shrimp, mussels, and pieces of fish.

frog catfish

A large predator with a massive head and a huge mouth. The short antennae are notable. Dark body color and whitish belly. Grows up to 25 cm. Accepts food from fish with white meat, shrimp, mussels.

Dimidochromis

A beautiful blue-orange predator. Develops speed and attacks with powerful jaws. Grows up to 25 cm. The body is flattened on the sides, the back has a round contour, the belly is flat. Fish smaller than a predator will certainly become its food. Shrimp, mussels, and clams are added to the diet.

All predatory fish in the wild and artificially kept are carnivorous. The diversity of species and habitats is shaped by many years of history and the struggle for survival in the aquatic environment. The natural balance assigns them the role of orderlies, leaders with the inclinations of cunning and ingenuity, who do not allow the dominance of trash fish in any body of water.

The use of Far Eastern herbivorous fish species in Ukrainian farms is not only economically profitable, but also beneficial for water bodies. The main object of pond fish farming is carp. But in recent years, herbivorous fish have become increasingly widespread and are used not only as valuable fish farming objects, but also as biological ameliorators. The industrial development of Far Eastern herbivorous fish (grass carp, white and motley carp) is the most promising. (Published in No. 05.2010)
They ensure maximum growth in fish productivity, help improve the sanitary and technical condition of water bodies, eliminating excessive overgrowth and “blooming” of water. The relocation of Far Eastern fish from Russia and China to Ukraine began back in the 60s of the last century. In our conditions, they grow and ripen well, but do not reproduce - they are bred artificially

White amur

This valuable, fast-growing commercial fish of the carp family reaches a weight of 50 kg or more. It feeds mainly on higher aquatic vegetation; it eats well meadow grass, alfalfa and concentrated feed. In the early periods of development, it feeds exclusively on zooplankton, from 15 days of age on small vegetation, and from a month of age on the main food. During the day, grass carp eats more plant food than its own weight. Favorite food is duckweed.

The green mass eaten by grass carp, passing through the intestines, enters the body of water, improving its biological productivity and living conditions for other fish species. Grass carp are used as ameliorator at different ages. The stocking rate, depending on the overgrowth of the reservoir and the age of the fish, ranges from 100 to 500 pcs/ha. Under natural conditions, the productivity of grass carp is 1-2 c/ha. But if the carp is fed with perennial grasses (sainfoin, alfalfa, etc.), you can get a fish productivity of over 3 c/ha. If there is a lack of vegetation, grass carp can switch to compound feed, but prolonged feeding with it provokes serious pathological changes in the fish’s body.

In the south of Ukraine and in cooling ponds, grass carp reaches sexual maturity at 4-5 years, in the north - at 8-9. Already in the first summer, with a planting density of 4-5 thousand pieces/ha of grown grass carp in ponds, the development of soft aquatic vegetation is delayed, duckweed is destroyed in large quantities, and the sanitary condition of reservoirs deteriorates. Replanting two-year-old grass carp at a density of 400-600 pieces/ha is effective, thanks to which it is possible to completely clear weakly or moderately overgrown ponds. In heavily overgrown ponds, at least 1000 two-year-old grass carp should be placed per 1 hectare, and even better, stock them with three-year-olds. If ponds, when heavily overgrown with reeds, become unprofitable for raising fish, invaded two-year-old grass carp can actively destroy the vegetation within just one growing season, making these ponds suitable for carp breeding. To thin out and destroy unwanted vegetation, only a few specimens are needed (10-50 specimens/ha), in exceptional cases - up to 100 specimens/ha of three-year-old grass carp.

For planting grass carp, flowing reservoirs with a depth in summer of at least 0.3-1 m are more suitable, which guarantee successful wintering of the carp. But if the water temperature in the reservoir in summer does not reach 16-18 ° C, you cannot count on a successful fight between carp and vegetation.

The technology for growing fish in complex reservoirs should be based on polyculture: in addition to grass carp, it is necessary to introduce pike perch, pike, white and bighead carp, and carp without feeding with compound feed. If the water bodies are inhabited by pike, which tends to eat young fish, for reclamation it is advisable to use grass carp at the age of 2 years and older, weighing at least 150-200 g.

This technology is widely used in the Irklievsky fish hatchery of herbivorous fish in the Cherkasy region. After the introduction of grass carp, this enterprise cleared all pond areas of more than a thousand hectares of aquatic vegetation, significantly improving the sanitary condition of the ponds and the production and financial indicators of the farm.

Silver carp

This fish in the southern regions and cooling ponds reaches 20 kg in weight. At early stages of development, it mainly eats small species of zooplankton (rotifers, nauplii, small crustaceans). On the 8th-9th day it feeds on microscopic algae - phytoplankton, the mass reproduction of which leads to “blooming” of the water and death of fish. Detritus occupies a significant place in nutrition. The daily diet of silver carp reaches 25-40% of its own weight. Does not compete in nutrition with carp and other valuable fish species. On the contrary, when they are grown together, a positive mutual influence is observed. Silver carp is ideal for eating algae in eutrophic water bodies. It reaches sexual maturity at 6-9 years of age in the north of Ukraine, in the south - at the age of 4-5 years, in cooling ponds - at 3-4 years.

Bighead carp

This partially herbivorous fish, along with plankton and detritus, also eats zooplankton. In appearance it resembles a silver carp, but has a shorter body and a large head. The filtration apparatus of the gills is highly developed.

The daily diet of bighead carp reaches 25-40% of its own weight. The juveniles feed exclusively on small plankton for the first two weeks, then switch to phytoplankton. Large individuals feed on phyto- and zooplankton. Two- and three-year-olds can eat only blue-green algae and still grow well. Bighead carp has the highest growth rate: in the southern regions it can reach a weight of 35-40 kg. But with a significant increase in stocking, it can compete with carp. Bighead carp reaches sexual maturity in the southern regions of Ukraine and cooling ponds at the age of 4-5 years. The spawning period extends from mid-July to the end of August. Fecundity averages 500 thousand eggs, but can reach 1.5-2 million. Embryogenesis occurs quickly, lasting 18-60 hours from fertilization to hatching.

When using intensive fish farming technology, stocking density is determined by a set of indicators: natural fish productivity, productivity due to the application of fertilizers, fish feeding, age and size composition of juveniles according to the formula:

For yearlings:

For larvae:

X is the amount of required planting material (individuals);

S - pond area (ha);

P - fish productivity (kg/ha);

M2 - mass of final product (kg);

M 1 - mass of planting material (kg);

B - % of final product yield from planting.

Recently, many farms have switched to a pasture form of fish farming, for which a set of polycultures of fish is used for the rational operation of ponds. When growing fish in a polyculture, planting calculations for each type of fish are carried out separately.

Herbivore priorities and risks

Breeding herbivorous fish on an industrial scale is possible exclusively through artificial reproduction. In Ukraine, almost all fish farms are engaged in this fishery, of which about 20 take part in the implementation of the state program “Reproduction of aquatic living resources in inland water bodies of Ukraine” for stocking the Kiev, Kanevsky, Kremenchug, Dneprodzerzhinsky, Kakhovsky, Dniester reservoirs with fish. , the lower reaches of the Dnieper, the Danube River, the Dnieper-Bug, Dniester estuaries and other reservoirs. The area of ​​inland reservoirs in Ukraine, which are used or can be used for growing fish, is more than 1 million hectares. These are ponds, reservoirs, rivers, lakes, estuaries, and cooling reservoirs for energy systems. There is also a significant number of thermal reservoirs, which primarily include cooling reservoirs of energy facilities. Their higher temperatures contribute to the normal development and growth of fish and the precocity of producers. Thus, female silver carp become sexually mature at the age of 3-4 years, bighead carp at 4-6 years, males of all species mature 1-2 years earlier than females, which reduces the maturation of fish from water bodies by 2-3 years. normal temperature conditions. It is recommended to use two-year-old fish with an average weight of 150-300 g as fish seeding material. Stocking rates are calculated in accordance with the food supply of the reservoir, the type of stocking and the feed ratio (for phytoplankton it can be approximately 50, for zooplankton - 7).

Sick fish must be caught in early spring before healthy fish begin to spawn. When small species of cyprinid fish are affected by ligulosis, the number of predators - pike perch and pike - should be increased. In pond farms located near reservoirs inhabited by fish-eating birds, in the fall it is necessary to completely drain the water from the rearing ponds, and treat their bed with quicklime or bleach. It is optimal to stock natural reservoirs with fish in late autumn or early spring, when the infestation of fish sharply decreases.

Literature:

1. Raising producers and exploiting broodstocks of herbivorous fish. Guidelines. - M., 1982.

2. Andryushchenko A.I., Baltadzhi R.A., Grinzhevsky M.V. ta in. Methods for increasing the natural fish productivity of staves. - K.: IRG UAAN, 1998.

3. Kozlov V.I., Abramovich L.S. Fisherman's Handbook. -M.: Rosagropromizdat, 1991.

OPINION PRACTICE

Grigory Poddubny,

director of the State Enterprise

"Irklievsky fish hatchery of herbivorous fish"

Herbivorous fish are an important resource in inland waters and a reserve for increasing the productivity of Ukraine” in terms of stocking the natural nature of inland waters. Through their implementation, it is possible to obtain in addition to 20 to 50% of valuable commercial products when growing herbivorous carp, improve the economic indicators of fish farms, and expand the range of farmed fish. Our farm is a fish hatchery for growing herbivorous fish - grass carp, white and motley carp, and annually takes part in the implementation of the state program “Reproduction of aquatic live fish in polyculture with carp without the use of compound feed, that is, only on natural feed ( vegetation, phyto-zooplankton, benthos, detritus), you can get fish products of 600-800 kg/ha.

In addition, herbivorous fish, especially grass carp, are not only one of the real reserves for increasing the fish productivity of ponds, but also biological ameliorators for clearing ponds of abundant aquatic vegetation.

On our farm, with the introduction of the technology for creating reclamation herds of grass carp, over the course of several years, all pond areas - more than one thousand hectares - were cleared of aquatic vegetation, as a result, the fish productivity of the ponds significantly increased, and their sanitary condition improved , as well as production and financial indicators of the economy.

Fedor Korchevoy,

Director of the Ichthyopathological Laboratory of the State Committee for Fisheries of Ukraine

Herbivorous fish (white and bighead carp and grass carp)

They are important objects of pond fish farming, and are also used to form the ichthyofauna of rivers, lakes, and reservoirs.

Procurement and selection of producers

Grass carp, silver carp and bighead carp do not breed in ponds, and

The only way to obtain eggs of these fish species is through the method of pituitary injections. In males, although the reproductive products mature without the use of pituitary injections, a stimulating pituitary injection is nevertheless necessary to obtain a large amount of sperm.

According to the Tropical Fisheries Research Institute in Malaysia (Malacca), the rate of maturation of herbivorous fish in pond conditions is influenced by the quality of food. It is advisable, especially during the maturation period, to feed the fish with food consisting of shrimp meal, rice bran and wheat flour.

In the breeding herd, the number of herbivorous fish varies by species. Considering that the production of silver carp in the southern regions, according to approximate estimates, is 85-90%, and grass carp - 10-15%, it is advisable to raise breeders in this ratio for individual species. In this case, a reserve of females of at least 50% must be provided.

Artificial fertilization of eggs allows you to reduce the number of males and have no more than 3-4 males for every 5 females. The annual replenishment of the herd of breeders due to the culling of old ones and those retiring due to injuries during the spawning campaign is approximately 25% of their number accepted for a given farm.

When raising pedigree young animals, natural productivity

no more than 400-500 kg/ha is accepted with the following approximate ratio:

Grass carp (without feeding) - not higher than 100 kg/ha,

Bighead carp - 100-150 kg/ha, - silver carp - 200-300 kg/ha.

The growth of producers over the summer is at least 1 kg. In this case, it is accepted

measures to maintain the food supply by fertilizing ponds, and for grass carp, with a lack of higher aquatic plants, by using terrestrial ones (clover, alfalfa, barley, etc.).

For sowing, special fields are allocated; several are sown on them.

crops, since monotonous and especially long-term feeding of one species leads to a decrease in its consumption. When calculating feed requirements

The average feeding coefficient for grass carp is “30”.

When growing grass carp, much attention should be paid to higher aquatic plants, since they cannot be replaced by mixed feed, grains, or other foods known for carp. Moreover, with a deficiency of these plants, serious functional disorders occur, causing growth retardation, puberty, and even mass death.

When planting breeding stock for wintering, the following standards are accepted: fingerlings - up to 200-300 thousand heads/ha, and older age groups - 100-200 c/ha of wintering pond.

Each type of breeder is placed in a separate wintering pond, and for other age groups of replacement young stock, separate keeping in wintering ponds by species is not necessary.

When a stable average daily temperature of 19-20 °C occurs, water is drained from the wintering ponds, the producers are caught and inventoried. They are then grouped by species, sex and degree of readiness for spawning.

Fish with injuries, signs of disease or deformities are rejected. Individuals, especially those that first spawn, whose readiness for spawning cannot be determined, are not used for spawning. They are planted in feeding ponds. Depending on the degree of maturity of the reproductive products, females are divided into three, and males into two groups (classes).

A characteristic feature that allows you to distinguish females

The difference between herbivorous fish and males is the presence of peculiar outgrowths - spines - on the inside of the pectoral fins.

In silver carp they are large and sharp; in the motley - less sharp, in the form of tubercles; Male grass carp have very small spines that feel

The inner surface of the pectoral fins is like sandpaper.

After sorting by species, sex and classes, the spawners are placed in small area (0.05-0.2 ha) pre-spawning ponds with a well-planned bottom and depths of 1.5-2 m, constant water exchange that prevents overheating of the water, where they are kept until obtaining sexual products.

To avoid over-ripening during this period, they should not be kept in small, well-heated ponds, and the spawning campaign should not be delayed longer than 25-30 days. For pre-spawning maintenance, spawners are planted in ponds at the rate of 1000 heads per 1 hectare (no more than 150 c/ha). The time for filling these ponds with water should not exceed 2-3 hours, and draining - 1.0-1.5 hours.

The timing of work on the artificial breeding of certain species of herbivorous fish due to different maturation periods of reproductive products is not the same. Work begins with silver carp and grass carp, and then after 10-15 days - with bighead carp.

The beginning of work on obtaining reproductive products depends on

climate zone. So, for Turkmenistan and Uzbekistan - in the first ten days of May, in the Krasnodar Territory and other areas with similar climatic conditions - in the second half of May, in Moldova - in early June, in the Volgograd and Astrakhan regions - in the second half of June. All these estimated dates may change depending on the characteristics of a given year.

The offspring of herbivorous fish have not yet been obtained in central Russia on an industrial scale due to temperature conditions. However, here too it is recommended to use the warm waters of the state district power plant, which will dramatically reduce the time required for raising spawners and provide the appropriate temperature conditions necessary for the early maturation of reproductive products and work on artificial fertilization of eggs.

Obtaining mature products

To increase the percentage of maturation of females, especially for the first time

spawning individuals, fractional pituitary injections are advisable, which stimulate the maturation of the ovaries in stage IV of maturity.

Directly during the pre-spawning period, changes in the ovaries take place in two stages: first- pre-ovulation, when the eggs mature, and second- ovulation, when the eggs are released from the follicular membrane that supports them in the ovary.

The first stage takes place under the influence of very small doses of gonadotropic hormone (preliminary injection), and in the second - large doses (permissive injection).

To stimulate maturation, the pituitary glands of mature carp, dried and degreased in acetone, harvested in the pre-spawning period, are used. They are administered to manufacturers in the form of an aqueous suspension prepared immediately before injection.

This or that amount of pituitary glands is poured into a small (30-50 cm") porcelain mortar and thoroughly ground with a pestle, and then moistened with a few drops of the solution, which forms a dough-like mass, which is again thoroughly ground.

This mass should be well crushed and not contain large fractions that could clog the syringe needle. Then boiled or distilled water or physiological solution (6.5 g of table salt per 1 liter of water) is added to the mortar and everything is mixed until a uniform suspension is obtained. The volume of suspension for preliminary injections is 0.5-1.0 ml, and for resolving one - 1.0-1.5 ml.

The needle is inserted deep into the tissue at an acute angle, under the scales (without piercing it),

and in order to prevent the suspension from leaking out, after removing the needle, the puncture site is pressed with a finger and massaged.

Before injection, females are weighed, measured, and marked according to requirements. During a preliminary injection, females are given 1/8-1/10 of the intended dose of gonadotropic hormone, and a day later - a resolving dose. When injecting, it is important to determine the most correct dosage of the pituitary gland, since if it is underestimated, favorable results cannot be obtained. At

At low dosages, caviar may not be obtained or not completely obtained.

At the permissive dose, the amount of pituitary substance usually ranges from 3-6 mg per 1 kg of female weight. When determining the dose, it is necessary to take into account not only the weight of the fish, but also the amount of its fertility. The more eggs a female has, the more the pituitary gland requires to fully produce them.

In practice, the dose is determined by multiplying the weight of the female by the amount of pituitary gland selected in the range from 3 to 6 mg, and this amount is adjusted in subsequent batches depending on how fully the females give off eggs.

For convenience, during preliminary injection, females weighing 5-7 kg are recommended to be administered 3 mg of pituitary dry matter, and larger ones - 5-6 mg.

For work, they usually use flowing males. However, to obtain a sufficient amount of sperm, males also undergo pituitary

injection. For males weighing 5-7 kg, it is enough to administer 4-6 mg of pituitary gland.

If it is necessary to obtain more sperm for large males (up to 10 kg), 12-15 mg of pituitary gland substance should be administered per fish. The injection is given to males an hour before the permissive injection to females. For 2-3 females they take one male.

To determine the resolving dose of the pituitary glands, you can use

nomogram depending on the dosage of the pituitary gland and body girth

For example, if a female weighs 10 kg and has a girth of 54 cm, then 1 kg of this female will require 5 mg, and 10 kg - 50 mg of pituitary substance.

After the injection of producers, the process of maturation of reproductive products requires only a temperature close to spawning and

favorable oxygen regime. All this can be done in small

(20-30 m) spawning ponds with constant water exchange, depth 0.8-1.0

m, with water discharge and filling within 30 minutes.

After injection, up to 10 producers can be planted in such a spawning tank. After injection, they can be kept in container baths made of tarpaulin, fiberglass and other materials.

Unfertilized eggs have a diameter of 1.1-1.6 mm. After hitting

The eggs become heavily watered, swell, and their diameter increases to 4-5 mm.

the volume increases more than 80 times, resulting in a significant reduction in specific gravity.

In order to ensure selectivity of fertilization, when fertilizing the eggs of one female, it is better to use the sperm of 2-4 males. In this case, sperm is collected before or immediately before fertilization, males are caught and the sperm is filtered from them directly onto the eggs. To inseminate 1 liter of eggs, 5 ml of sperm is enough.

When pre-harvesting, the sperm is filtered for 30-60 minutes. before receiving eggs from females. To do this, in the same way as females, males are caught, their abdomen is thoroughly wiped with dry gauze and, stroking it from top to bottom, the sperm is filtered into dry, clean test tubes (the most convenient are 15 cm long and 3-4 cm in diameter) or jars separately from each male. When straining, make sure that it is clean and that blood, mucus, intestinal contents, and water do not get in with it.

The first drops of sperm should not be taken. When the tubes or jars are filled with sperm, they are closed with cork stoppers or cotton swabs and stored in a thermos with crushed ice until the eggs are fertilized. For these purposes, a wide-mouth thermos with a volume of 0.5 liters or more is recommended, with 1/3 of it filled with ice and covered with a thin layer of cotton wool or gauze folded 4-5 times.

The quality of sperm is also of great importance, for which it is pre-evaluated. Benign sperm is distinguished by its white color and creamy consistency, while low-quality sperm is liquid, with a greenish or bluish tint.

Collection and insemination of eggs

It is more convenient to give the injection in the evening (21-22 hours), since all subsequent

labor-intensive operations (receipt of eggs, their fertilization, distribution among

devices, quality control) will be carried out in daylight.

For better and more complete use of spawning ponds and equipment, as well as to facilitate the work of service personnel, it is advisable to receive caviar not daily, but every other day.

Before taking the reproductive products, the spawners are caught, for which the water in the spawning tank is first lowered, which facilitates the movement of workers over the entire area of ​​the cage.

Catching is carried out using a sleeve made of burlap or other material 1-3 m long. On one side, the sleeve is placed on a metal hoop with a diameter of 30-35 cm. The sleeve is carefully put on from the side, and another worker simultaneously grabs the tail peduncle with his hand covered with gauze.

A fish caught in this way quickly turns over in the water with its belly up, and in order to avoid loss of reproductive products, the genital opening is clamped with a finger and in this position the fish is taken to shore, where it is carefully

Wipe off water and mucus with dry gauze.

The eggs from each female are strained into a separate basin, separately fertilized with the male’s sperm using the dry Russian method, and separately counted by volume or weight.

The entire operation of straining the eggs and fertilizing them is carried out in the shade or under a canopy in a dry, clean, corrosion-free basin, and the eggs should flow smoothly along its walls. Mature eggs flow easily from the female's genital opening and have a color from bluish-gray to bright orange, while overripe eggs are cloudy white.

1 ml of unfertilized eggs usually contains: grass carp - 800-1000 eggs; silver carp - 900-1200 eggs; bighead carp - 600-800 eggs.

Usually the same number of eggs is contained in 1 g of unfertilized eggs. Depending on the size and age, the fertility of carp and silver carp ranges from tens of thousands to 1.5-2 million eggs, and on average in females weighing 7 kg - 500 thousand eggs. The fertility of fish is calculated by the number of eggs in the ovary. Usually, the more eggs in the ovary, the smaller it is.

To determine fertility, the ovary, which is in a pre-fluid state, is weighed, then 1 g of caviar is taken (and for large caviar, more) and the number of eggs is calculated. Next, the ovary is weighed. Quantity

caviar in 1 g is multiplied by the weight of the ovary and absolute fertility is obtained.

In addition to absolute fertility, there is also working fertility. In nature, not all eggs are fertilized, although with artificial insemination the fertilization rate will be higher. When squeezing the eggs, some of the eggs remain in the ovaries and body cavity of the female.

In fact, the resulting caviar is the working fertility. The value of working fertility is the basis for calculating the need for the required number of females.

The number of developing eggs is affected not only by age, size of fish, temperature and oxygen. Producer nutrition matters

having a significant impact on the degree of development of the gonads.

Experiments with palia (Salmo fontinalis) showed that with abundant nutrition it produced 910 mature eggs, with a half-ration reduction - 520, and with 1/4 of the diet - 405.

However, overfeeding is harmful and leads to infertility due to obesity and degeneration of eggs. Degeneration can occur with improper maintenance and unsatisfactory conditions.

When fertilizing the eggs, the required number of tubes are removed from the thermos, some of the milk is used, and the remaining milk in the tubes is again placed in the thermos. Heating sperm tubes is unacceptable. Keeping them in a thermos on ice for 10-12 hours does not reduce the fertilizing ability of sperm. The active movement of sperm in water lasts 15-30 seconds, and for some of them longer. At the same time, with increasing water temperature, the death of sperm increases.

The sperm is carefully spread over the calf with a bird feather, then

fill the basin with a small amount of water and stir the caviar into it with a feather and gentle rocking. The water takes on a milky hue. After 2-3 minutes, the water is drained and new water is added. The water is changed until the eggs are washed from sperm, lumps of mucus, blood, and scales.

Fertilized eggs swell greatly (its diameter increases from 1.2 to 5 mm or more), becomes lighter, acquires buoyancy, and no later than 5-10 minutes. After fertilization, it is placed in incubation apparatus. When changing water, care must be taken and

be careful, since fertilized eggs can be drained along with the water.

To incubate the eggs of herbivorous fish, Weiss apparatuses, which are cylindrical glass vessels tapering downwards, are often used. The Weiss apparatus for incubating small eggs has a volume of 8 liters and holds about 50 thousand eggs.

For better washing of each egg with a current of water coming from bottom to top under some pressure, it is kept in suspension, for which the lower hole is tightly closed with a stopper, a metal tube is inserted into it, through which water is supplied under pressure. Its currents rise up along the walls of the vessel and carry up the eggs located in the apparatus.

Depending on the pressure and flow of water at a particular height, the rise of the calf stops, and it sinks down until it is again picked up by the flow of water and raised up.

The fertilized eggs are in a state of continuous movement in the apparatus, which ensures good washing with water. In the acclimatization laboratory of VNIIPRH, larger capacity devices (from 50 to 200 l) have been designed for incubation of eggs of herbivorous fish.

A 50-liter apparatus can hold 350 thousand eggs, a 100-liter one can hold up to 750 thousand eggs, and a 200-liter one can hold 1.5 million eggs.

Egg incubation

Incubation of eggs of herbivorous fish is carried out in a special

hatchery located next to the spawning ponds. Particular attention is paid to the quality of water supplied to the hatchery.

When heating water in the workshop, it should be fed into the devices through a pool, where air bubbles that attach to the eggs and carry them out of the devices are removed. It must be clean, uncontaminated, free from mechanical suspension.

To prevent predatory cyclops from entering the incubation apparatus along with the water, damaging large numbers of eggs and larvae, a filter made of a nylon sieve of at least No. 46 is installed at the head of the water intake.

Before loading the devices with fertilized eggs, the incubation workshop

Prepare accordingly:

Thoroughly wash all fish farming equipment and

if necessary, disinfect it;

Set the water flow rate;

Prepare the necessary utensils (enamel basins, buckets with

lids, polyethylene mugs, etc.), spare

incubators and thermometers, as well as journals for recording the development of eggs and free embryos.

Hatching apparatuses are loaded with caviar in polyethylene mugs

directly from the pelvis in which artificial insemination was performed.

When performing this operation, be careful not to injure the calf. To do this, when collecting it in circles, do not touch the walls of the pelvis, and in order to prevent caviar from being washed out of the apparatus when loading it, it is necessary to first reduce the water level in them by 1/3 of the volume.

After loading the incubation apparatus, pay attention to regulating the water supply so that the not yet fully swollen eggs are in very slight movement in the lower half of the apparatus (water flow -0.4-0.5 l/min.).

Subsequently, as the eggs swell and increase in volume, the water flow is increased to 0.7-0.8 l/min. Caviar is poured directly from the basins into larger capacity devices. Water exchange in 50-liter VNIIPRH devices is 3.4 l/min, in 100-liter devices - 7.0 l/min, in 200-liter devices - up to 10 l/min.

The percentage of fertilized eggs of each female is individually determined in a Bogorov counting chamber at the stages of crushing from 4-8 blastomeres to morula (100 eggs are viewed). The obtained data is entered in the appropriate column of the hatchery workshop journal.

When using benign eggs, the fertilization percentage can be no lower than 90, the yield of free embryos is 70-80% of the amount of eggs laid. The loss of eggs during the incubation period may vary depending on the incubation conditions, improper installation of incubation apparatus, sharp fluctuations in water temperature, as well as the quality of the reproductive products.

The optimal water temperature for the development of eggs and free embryos is not lower than 18-19 ° C, and reducing it beyond 17 ° C not only slows down the development of eggs, but also causes significant waste and leads to the hatching of underdeveloped and malformed embryos. At an optimal temperature of 21-22 °C, the duration of incubation is 23-33 hours, and at a temperature of 27-29 °C it is reduced to 17-19 hours.

The high mortality of eggs in the apparatus and free embryos in cages also causes sharp fluctuations in temperature, dropping from optimal during the day to 15-16 °C at night.

Great influence on both the percentage of fertilized eggs and the yield

prelarvae are influenced by the conditions of keeping the producers in

Pre-spawning period. With extended spawning periods and prolonged

products deteriorate and waste increases at certain stages of development.

During the incubation period, caring for eggs in the apparatus consists of regulating the water flow regime, which eliminates both the removal of eggs (with increased water supply) and sedimentation in the lower layers (with insufficient water supply), which leads to mortality and death, as well as in the selection of dead eggs using a siphon (from a thin rubber hose).

Dead caviar, having a cloudy whitish tint, floats to the upper layers, is clearly visible and is easily removed. When it is removed, the water supply to the apparatus is reduced by half and the entire operation is carried out 8-10 hours after the start of incubation, at the stage of completion of gastrulation.

To determine the expected release of prelarvae, the percentage of dead eggs and eggs with malformation is determined several hours before hatching.

developing embryos, counted together with dead eggs.

Keeping hatched larvae alive

Typically, mass hatching of embryos occurs within 1-3 hours, but

sometimes it drags on for a longer period, even up to a day. Friendly hatching is achieved by reducing the water supply to the devices by 3-5 times compared to the normal flow rate.

The larvae are transplanted into cages installed in concrete pools 1 m deep. The cages are made from a nylon sieve No. 18-20 measuring 60x60x45 or 70x70x45 cm. When installed, they are immersed in water at least 30 cm and make sure that the bottom does not sag. Up to 2500 larvae are planted in such cages.

Caring for cages with larvae is to ensure proper oxygen conditions, for which the water is aerated. This is especially important during the period when they are still inactive and lie at the bottom of the cage. Remains of egg membranes and dead embryos are also removed using a rubber bulb with a glass tube inserted into it. In such cages the larvae are kept until they move to

mixed nutrition and different times depending on the temperature:

At 18-20 °C - 90-100 hours; - at 20-23 °C - 80-85 hours; - at 26-27 °C - 48 hours.

Waste during the growing period in cages under favorable conditions

temperature conditions and water exchange are low. The survival rate from fertilized eggs to the larva, which has switched to mixed nutrition, is not lower than 50%. They count by eye. To do this, use light-colored dishes - a basin, bowl, etc. A certain number of larvae are counted and their concentration is counted, comparing with the existing standard.

More often, hatching larvae of herbivorous fish are kept in Savin apparatus with a volume of 200 l and a water flow of 8-10

L/min. For this purpose, incubation devices are usually attached to the Savin apparatus,

and the larvae flow through the hoses along with the water and are concentrated in the holding apparatus.

The aging period, as in cages, depends on the water temperature (3-4 days). At this time, the larvae begin to swim in a horizontal position and switch to mixed feeding, which coincides with the filling of the swim bladder with air.

Growing larvae

After keeping the larvae in cages or Savin apparatuses, they

transported for further cultivation to other farms, or grown to more viable stages, or immediately transplanted into nursery ponds. The freed cages are thoroughly cleaned from fouling with a brush in running water, removed from the frames and washed with detergents, and then dried, always in the shade.

There are several ways to raise larvae that have switched to mixed nutrition. They are most common in fry (seedling) ponds of carp farms, as well as in well-reclaimed ponds of other categories with a well-planned bottom with an average depth of 0.5-0.7 m. A litter trap is installed on the water supply structure, and a fry catcher is installed on the discharge structure .

The nutritional regime is of utmost importance when raising larvae. The concentration of food organisms should be at least 1000-1500 specimens/l. In this case, animal organisms should prevail over plant organisms, and in the first days zooplankton should consist mainly of small forms, and in the second half of growing - of larger ones. However, for silver carp, large forms of zooplankton (cyclops, daphnia) are inaccessible throughout the entire period of larval development.

In relation to larvae, many species of invertebrates are predators, and the most widespread are cyclops, as well as beetles, bedbugs, their larvae, dragonfly larvae, etc.

To prevent the entry of predatory forms from the water supply source, a special trap is installed at the water supply structure, for which a conventional litter trap covered with a nylon sieve No. 32 is used.

Delays the development of predatory forms and reduces the period from filling ponds with water to their stocking. The timing of rearing is determined by the achievement of viability, when the larvae begin to consume all and most small and large food organisms, including predatory ones, which for most species is observed when the larvae reach a length of 11-12 mm and a weight of 15-20 mg.

For the conditions of the Krasnodar Territory, the growing time is on average 10 days, which makes it possible to use the same ponds twice. IN

Prepared and summered ponds with good soil and climatic conditions

conditions, you can plant up to 3-4 million larvae per 1 hectare. When applying fertilizers, these rates can be raised to 6-7 million units/ha.

Draining of ponds and catching larvae is carried out at night, when the temperature of the water in the surface layers drops, the larvae sink into deeper layers and, with the flow of water, quickly go into the catcher, from where they are caught with a net and transferred to basins or other containers. The net, at the bottom of which the larvae accumulate, is moved after a basin or bowl filled with water is placed under the bottom.

The yield of grown larvae is not lower than 60-70%. To increase the yield, larvae of herbivorous fish are raised in trays before release into ponds. The trays are placed in one or more rows, in pairs, at a distance of at least one meter under a canopy or in a sufficiently lit and ventilated room.

The most common are fiberglass 3-trays

size 4.5x0.7x0.5 m with a working volume of water 1.1-1.2 (up to 1.5) m For

increasing rigidity, an iron frame is made.

The cone or spherical shape of the trays makes them easy to clean,

gives additional rigidity and makes it easier to catch farmed fish.

To prevent the larvae from leaving the tray, use a frame with a nylon sieve No. 18-25. Water for tray farming is supplied through pipes equipped with flutes with nylon screens No. 32-35 to prevent harmful fauna from entering the trays.

The water flow rate in the trays is 8-10 l/min. The dissolved oxygen content should be above 5 mg/l, optimal 6-8 mg/l. The water temperature in the trays is from 20 to 30 °C (preferably 25-30 °C), sudden temperature changes are unacceptable. The water flow in the trays is stopped or made minimal before planting or catching the larvae, as well as at the time of feeding, after which the flow is brought to normal.

For rearing, 3-4 day old larvae are used. They are grown at a water temperature of 22-24 ° C for 10-15 days, and at a temperature of 26-29 ° C - for 7-8 days. Planting density is 100-150 thousand pieces/tray (at least 60-80 thousand pieces/m3). Live and plant foods are used for nutrition.

The yield of fry after growing in trays is:

With a planting density of 15-20 thousand pcs./m3 - 98-100%;

At 30-60 thousand pieces/m3 - 80-82%;

At 100-120 thousand pieces/m3 - 60-70%.

Raise larvae of herbivorous fish for more than 15 days

impractical, as cases of cannibalism are possible.

Questions for self-control:

1. How are producers procured and selected?

3. 4. 5. 6.

How are mature products obtained?

How are eggs collected and inseminated?

How are eggs incubated?

How are hatched larvae kept?

How are larvae raised?

Size: px

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Transcript

1 Herbivores Ekaterina Nikolaeva text: apple no (3) Just like vegetarian people, herbivores are found almost everywhere. They are not found except in Lake Baikal, where pure meat-eaters live. Scientifically, herbivores are called phytophages (from the words “phyto” plant and “phage” eater). Let's consider the biological characteristics of obligate vegetarians, that is, fish in which the plant component predominates in their food. There are few of them in the domestic ichthyofauna. These are representatives of carp fish: several species of carp and silver carp. Amur is a breeding object for stocking reservoirs with fish. 166 Fish with us 12/2008

2 Food chain If you arrange all the inhabitants of a reservoir in a row according to the nature of their diet, you will get a trophic (or food) chain in which each link serves as food for the next. There are three main groups of hydrobionts present in the reservoir. The food chain of them will look like this: aquatic plants (lower and higher) primary production; invertebrates (zooplankton, zoobenthos) intermediate products; fish final products. Adult phytophages turn out to be the final participants in the shortest food chain: algae (higher aquatic vegetation). That is, they are the most energetically favorable final products. Predatory fish have the longest trophic chain: algae zooplankton benthos small fish predatory fish. For humans, the final product in the food chain in water bodies is fish. When moving from one trophic level to another, 80-90% of energy is lost, and only 10-20% is absorbed. That is, with an extended food chain, energy costs to obtain the final product () increase many times over. Thus, -phytophages use their food to build their own tissues, and not to intermediate links in the form of benthos, for example. Therefore, these grow much faster than predatory ones and are actively used for breeding. Cupid This is the beautiful name given to two cyprinids, which even belong to different subfamilies. One of them is black cupid. But it eats shellfish, and although it is also used to clean water bodies, it is not our character. Another fish, white carp, is a typical representative of phytophagous fish. One of the largest carp fish reaches 120 cm in length and weighs up to 30 kg. The body of grass carp is elongated, not flattened laterally, and the scales are dense. The mouth is semi-inferior, its posterior corner is located strictly under the anterior edge of the eye. The pharyngeal teeth are double-rowed; moreover, they are wide and flat, capable of grinding plant foods well. The back is greenish-gray, the sides are grayish with a golden tint. Outwardly, it is very similar to black carp, but only lighter. Initially, this fish lived in the middle and lower reaches of the Amur and other Far Eastern rivers, as well as in the lowland rivers of China. Mass settlement of our water bodies with carp began in the first half of the 60s of the last century. And this is perhaps one of the most successful examples of acclimatization. Grass carp, as well as other phytophagous fish, are characterized by seasonal migrations over short distances. Juvenile grass carps, after the yolk sac of the larvae is reabsorbed, moves to the coastal zone, where it feeds until the end of summer. And in the fall it goes to deep places, into channels or riverbeds, and spends the winter in pits along with its peers, but not with its older relatives. Adult carps, after overwintering, sometimes enter the lakes, but always return to the spawning grounds in the river bed. After spawning, these fish break up into small flocks, moving along the floodplains to floodplain lakes, where they begin to feed intensively, and in winter, as a rule, they stop feeding. They gather in large flocks in wintering pits or simply in deep places. Like some other cyprinids, the special skin glands of cupids secrete mucus, in which the fish appears as if in GOLIATH -60 О С òëappleóí fl ÒÚÓÔ Ç ÒÓÍËÈ ÔÓ ÂÏ ìòúóè Ë Ë Ë òëappleóíÓ ÍÎ 1 3 PU Zylex 11 PU Zylex ÒÔÎ Kametik appleâíî Ï SUPER WARM CANADIAN FOOTWEAR Made in Canada -40 O C Tel.: (495) (multi-channel) ICECRUSHER ÅÖëíëÖããÖê! Made in Canada Made in Canada fl Apple's price AppleÏÓappleÂËÌ Ò ÔappleÓÚÍÚÓÓÓÏ, ÔÔappleÓÚË ÓÒÚÓfl ËÏ ÒÍÓÎ ÊÂÌË ÇÒÓÚ : 37 ÒÒÏ

3 Physiological features The intestines of herbivorous fish are much longer than the body length (two to three times in carp, times in silver carp). Silver carp have special adaptations for feeding on phytoplankton. Thin, closely spaced gill rakers are connected to each other by transverse bridges, forming a “sieve”. The algae retained by the gill mesh are compressed into a lump due to the interaction of the pharyngeal teeth, strongly compressed from the sides, covered with a cornea instead of enamel, and a millstone covered with a soft mucous membrane. The bolus of food then enters the long intestine. Herbivores eat little but often. They need food after 2-3 hours, and by morning they are very hungry. The characteristic large scales and lower mouth make the cupid very recognizable. When raised in ponds, grass carp becomes omnivorous, willingly consuming a variety of aquatic vegetation, plant nutrition, and animal feed. cocoon. Thread-like particles of this cocoon can even float on the surface of the water, like pasta, and thereby unmask the wintering places of cupids. By the way, in other seasons, places where there is amur can be easily identified by the abundance of floating feces, which look very similar to the feces of waterfowl. Spawning in domestic cupids is usually portioned, in contrast to cupids from Chinese rivers, for which it is one-time, one-time. The female lays about a million eggs, which is quite a lot for carp fish. By the age of three weeks, having reached a length of about 15 mm, juvenile carp feeds, like juveniles of other carnivorous fish, on plankton and benthos, but already begins to eat a lot of algae. However, for now, its diet is dominated by invertebrates: daphnia, chironomids and various crustaceans. And when the fry reaches 3 cm, it switches to feeding only plant foods. Juveniles and underyearlings of carp feed best at water temperatures of C, and when it drops to C, the amount of food they consume is halved; at a temperature of +10 C they stop feeding altogether. At the end of autumn and beginning of winter, when the water becomes colder than +5 C, carp stops responding not only to food, but also to other environmental factors. In terms of their diet, adult carps stand apart from all other fish, including herbivores. Their diet consists almost entirely of aquatic plants, most of which is higher aquatic vegetation, unlike many other fish, which constantly or occasionally consume phytoplankton. Amur is even called “grass carp” because it eats reeds, cattails, urut, and pondweed in reservoirs. If you offer him any terrestrial vegetation, he will consume that too. So, he eats cut grass, beet and potato tops, cabbage and lettuce leaves that fall into the water. Cupids sometimes jump out of the water, grab green leaves and even stems of plants that hang over the water, and eat them with a chomping sound. In water bodies of the temperate zone, grass carp has a very high growth rate: by the age of two its mass reaches 1 g, by the age of five it weighs 3 kg and has a length of 40 cm, and the weight of a seven-year-old carp is more than 10 kg with a length of no more than half a meter. It grows maximum in May June; least in September. This fish is used not only as an object for breeding, but also for other purposes, such as reclamation. After all, by eating aquatic vegetation (and on a summer day it eats as many plants as it weighs), cupid cleanses the beds of rivers, lakes, power plant cooling ponds and irrigation canals. Experience shows that by utilizing the aquatic vegetation of ponds and lakes, which is practically no longer used by anyone, this fish not only gives a high increase in its own weight, but also improves the hydrological regime of reservoirs, cleans them and thereby contributes to the development of a natural food base for other fish. The best effect is achieved when three-year-olds and older fish are introduced into natural reservoirs. Grass carp is not too demanding on the oxygen content in water and is resistant to infectious diseases. In water bodies of the temperate zone, the greatest danger to juvenile grass carp is coastal pike. When raised in ponds, grass carp becomes omnivorous, willingly consuming a variety of aquatic vegetation, plant nutrition (vegetables, bran, cake), and animal food (small fish, worms, insect larvae). You just have to be careful, because cupid is capable of completely destroying all aquatic vegetation in a small body of water, which can lead to a disruption of the ecological balance and the death of the rest of the ichthyofauna. Silver carp This is one of the most easily recognizable representatives of the carp family. It is quite easy to distinguish silver carp from its carp relatives. All silver carp 168 Fish with us 12/2008

4 (subfamily of carp fish) are distinguished by the shape of their head with a wide, convex forehead and low-set eyes, shifted to the sides of the head below the middle of its height. They are characterized by small scales, a short dorsal fin, and the absence of spiny rays in the dorsal and anal fins. This group of silver carp includes the Amur silver carp, or stomping carp, the South Chinese bighead carp, Indian tinnichts and the common silver carp, or white silver carp, which is familiar to many. Silver carp originally inhabited the rivers of East Asia: from the Amur in the north to Southern China in the south. This is another successful example of acclimatization. It has taken root well in many countries of Southeast Asia and in our country (back in Soviet times). Silver carp is a pelagic fish, that is, it stays in the water column. The record fish caught weighed about 50 kg. As soon as the fry switches to active feeding, its food initially becomes zooplankton and partly phytoplankton. And when the fry reaches 16 mm, it completely switches to feeding on phytoplankton, eating it in large quantities. In winter and food supply Phytoplankton is a collection of plant organisms that inhabit the water column of marine and fresh water bodies and are passively transported by currents. Phytoplankton includes all plant organisms, which make up about 90% of the entire plant kingdom. They are represented by protococcal, diatom, green, blue-green and many other groups of algae. Zooplankton are animal forms of plankton. The main representatives of the simplest unicellular animals in the spring the main food of adult silver carp is detritus, in the summer and autumn phytoplankton. Moreover, when switching to feeding on algae, its intensity in silver carp increases sharply compared to the winter “detritus” period. Like grass carp, silver carp overwinters at depth, in pits, where it lies practically motionless until spring warming. Younger individuals stay closer to the surface of the water in small schools. Like cupid, in cold water it does not react to external stimuli; the only thing that silver carp can react to in winter is the smell, since this one has a sense of smell like a dog. But his winter sense of smell can only be affected by synthetic flavors. Natural scents work worse. In summer, the most effective baits are natural: a mixture of cake, crackers, bran and hemp. Groundbaits with a sharper smell scare him away. The ideal time for a fisherman is when silver carp show feeding and locomotor activity. This happens at the end of July, in August and Silver carp cannot be confused with other fish of the carp family. in the first ten days of September. Nevertheless, in winter you can catch a lot of these wonderful fish, but it is much more difficult to do so. The main thing is to find a place where there are a lot of hungry silver carp. Although in winter the silver carp becomes a detritivore, it never digs at the bottom. It is necessary that the food particles do not lie motionless on the bottom, but are suspended and move slightly due to water fluctuations. This is, in fact, how (ciliates, amoebas), rotifers, lower crustaceans, larvae of mollusks, larvae and adult forms of some insects, and fish larvae behave. Detritus (from Latin detritus abraded) are small particles of organic or partially mineralized matter suspended in the water column or settled to the bottom of a reservoir. Detritus is formed from dead plants and animals and their excretions; microorganisms live in it. Detritus serves as food for animal detritivores and phytophages in winter. their favorite phytoplankton. Like all other phytophages, when silver carp does not have enough food, it perfectly eats insects and crustaceans, sometimes not disdaining small fish. Experiments have shown that, all other things being equal, hungry silver carp prefers animal food rather than plant food, that is, animal baits are more effective. Ichthyologists studied the taste preferences of herbivorous fish and found that of the various granules with bitter, sour, sweet and salty tastes, herbivores prefer granules with sucrose. Anglers should take this information into account when making fish baits at home. Among natural plant baits, it is good to use a reed stalk, clover and other plants convenient for planting. Herbivores are quite sensitive to weather conditions. They are most active when it is warm and there is light rain. The silver carp is very cautious and timid, and the rain does a good job of camouflaging a person on the shore. By the way, silver carp, unlike many other fish, distinguishes colors and hates red and orange. You should look for this fish at the border of the pit and coastal vegetation, or you can navigate by bleak and roach: if there are a lot of these fish, there is probably a silver carp nearby. Fish with us 12/

5 Phytophages and oxygen In summer, the influence of phytophagous fish on photosynthesis and, accordingly, on the amount of oxygen dissolved in water can be significant. Phytophages sometimes “knock out” vegetation in such a way that the oxygen in the reservoir becomes significantly less. And in winter they switch to Interestingly, when there is noise or knocking, silver carp sometimes jumps sharply out of the water, quite high up to 4 m. The famous ichthyologist Soldatov said that they feed mainly on detritus and thereby, on the contrary, increase the content of dissolved oxygen in the water, since detritus releases large amounts of carbon dioxide. But the winter influence of phytophages is still not very noticeable, since other factors are more responsible for oxygen. In the Lower Volga and Akhtuba, silver carp are often caught on the hooks of spinning anglers. During his expedition along the Amur and Ussuri rivers, he more than once had to deal with this fish, “which sometimes literally covered the motor boat and the boat in tow.” People sitting in the boat had to beware of bruises that could be caused by these rapidly jumping out of the water. When the silver carp does not have enough food, it eats insects and crustaceans, sometimes not disdaining small fish. name: D. Silver carp and grass carp have now begun to be intensively bred in fish farms, but in China they have been grown for more than 2000 years! Silver carp can be grown in a pond together with fish of other species, since it is not a food competitor for any of them. For it, unlike grass carp, there is no need to plant special plants in reservoirs, and phytoplankton is most often quite sufficient in feeding reservoirs. The bigheaded carp, or bighead (Aristichthys nobilis), is close to the common silver carp, but has a larger head and longer pectoral fins (they extend beyond the base of the ventral fins and are darker in color). This is a large, fast-growing, heat-loving fish, common in the rivers of China, south of the Amur basin. Along with plant foods, zooplankton plays a significant role in the diet of adult bighead carp. In this regard, the intestines of the bigheaded silver carp are shorter than those of the white carp, and the long and thin stamens do not grow together. In the northern and central regions of China, bigheaded carp becomes sexually mature at the age of 6-7 years (weight about 15 kg), in the south at the age of 4 years (weight 7 kg). Its fertility in the Yangtze is 1.1 thousand eggs. Motley carp begins to spawn somewhat later than white carp, spawning in the middle and bottom layers of water. Now this is a very popular fish among fish farmers. Of course, dividing fish into vegetarians and “meat-eaters” is quite arbitrary, since most fish still have a mixed diet. But still, herbivores stand a little apart from the rest in all aspects of nutrition. And when catching these wonderful fish, their characteristics should be taken into account. Then, both in summer and winter, the chances of being caught will increase significantly. 170 Fish with us 12/2008

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