Herbivorous fish. Predatory fish

In experiments by ecologists, grass carp, considered an exclusively herbivorous fish, preferred freshwater amphipods to its favorite algae.

Like land animals, fish are divided into carnivores, herbivores, and omnivores. Although it seems clear that different fish will prefer different underwater vegetation, there has been little detailed research on this topic. Elisabeth Bakker from the Netherlands Institute of Ecology set out to find out the tastes of two fairly common freshwater fish, rudd and grass carp. Both were offered five types of algae, the weight of each “dish” was measured before and after the experiment to find out what the fish liked most.

Grass carp, avowed vegetarian and secret predator (photo by cotaro70s).

At first, the results were very banal. The fish paid the least attention to algae with toxins, and most readily ate species rich in nutrients, preferring those that contained the maximum nitrogen. But then something unexpected turned up. Along with algae, the fish were offered amphipods. And when the fish had to choose between their favorite algae and crustacean, they ate the animal “snack” first.

In the case of the rudd, this is not so surprising - this species is considered an omnivore. But grass carp, a strict vegetarian, is believed to have behaved in exactly the same way. Ecologists published the results of the experiments in the journal Freshwater Biology.

Video: How to replace meat. Vegetarian table

Why grass carp suddenly switched to meat remains a mystery. The choice, however, cannot be called unsuccessful: amphipods are definitely richer in organic nitrogen than underwater vegetation. Perhaps, the authors of the article argue, there are no strict herbivores under water at all, and all so-called vegetarians periodically diversify their menu with animal food.

One way or another, these data allow us to reassess the role of grass carp in freshwater ecosystems. This species is often used as an effective environmental tool to keep algae under control so that it does not overwhelm the entire body of water. Now fish farmers and ecologists have to think about what else grass carp can eat, freeing the reservoir from excess algae.

Cultivation of herbivorous fish or maintenance of ponds is the main source of fish on the country's market shelves. Pond fish farming technologies are developing and changing due to changes in the historical, political and economic situation in Russia.

The pond culture cycle for carp and other herbivorous fish traditionally takes two to three years. The feeding of herbivorous fish in ponds is carried out through the cultivation of polyculture and fertilization of the ponds. Refusal to use artificial feed with mineral fertilizers makes it possible to obtain annual growth in all types of ponds (nursery and fattening).

Types of herbivorous fish

Which fish are herbivores? The list of herbivorous fish in Russia includes:

• Silver carp is white and motley.
• Carp.
• White amur.

These fish, thanks to their natural characteristics, easily take root in many countries, while maintaining their taste characteristics.

White amur

This one belongs to the carp family and is characterized by rapid growth. There are known cases of grass carp gaining weight up to 50 kg. Any vegetation of reservoirs, meadow grasses, as well as concentrated food is suitable for feeding carp. The diet of grass carp is determined by its age.

The amount of food consumed by grass carp often exceeds its body weight.

Cupid is called the natural filter of the pond. The algae eaten by it passes through the intestines of the fish and again ends up in the reservoir, creating comfortable conditions for other fish to live and reproduce. The number of reclamation fish depends on how overgrown the pond is with algae and ranges from one hundred to five hundred units of grass carp per hectare.

To increase productivity, it is recommended to introduce perennial grass feed into the fish diet. Alfalfa or sainfoin will do. With low vegetation in the pond, grass carp can feed on compound feed for some time. But you shouldn't abuse it. This can lead to the development of serious pathologies in the population.

The readiness to reproduce in grass carps depends on the region of residence. Thus, in the southern regions of the country, grass carp reaches sexual maturity at five years, and in the northern regions at eight.

By adding grass carp in numbers of up to 600 per 1 hectare, you can clean up slightly overgrown reservoirs. For moderately and heavily overgrown ponds, the number of grass carps should be increased to a thousand individuals per hectare. The introduction of young white carp helps to clean up unprofitable reservoirs overgrown with reeds in one growing season and prepare them for raising carp fry.

But in order for grass carp to prove itself as a land reclamation agent, it needs to create special conditions. So, the depth of the pond should not be less than half a meter. This condition is necessary for fish to successfully winter. And ensure water heating in the summer months to 18°C.

The technology for growing planting material for herbivorous fish in complex ponds is based on polyculture. Such representatives of the fish world as silver carp (white and bigheaded), carp, pike and pike perch get along well with grass carp. Why might the number of herbivorous fish decline sharply? The presence of pike in the pond guarantees that it will eat young carp. Therefore, to successfully remove algae, two-year-old grass carp, weighing over two hundred grams, are planted.

This technology has been successfully used for a long time by the Saratov fish hatchery of herbivorous fish. After replanting two- and three-year-old grass carp, the enterprise managed to get rid of algae and reeds on an area of ​​over a thousand hectares, which, in turn, led to an improvement in production and financial indicators.

Carp

Carp is the first name that comes to mind when answering the question which bony fish is herbivorous. In fact, carp is a domesticated carp. A characteristic feature of its digestive system is the absence of a stomach. Therefore, the carp devotes its entire life to searching for food. Fortunately, it is unpretentious in food - with equal pleasure, carp absorbs algae and other aquatic vegetation, insect larvae, midges and small plankton.

Carp is a long-lived fish; it can live for about half a century. Of course, it makes no sense to farm carp for such a long period of time.

Carp is the most popular species in fish farms. Carp farming accounts for up to 70% of all herbivorous fish.

The popularization of breeding these fish is caused not only by the diversity of what carp eat, but also by its undemanding nature in care and maintenance. This fish easily endures difficulties and adversities - cold temperatures and lack of oxygen.

There are three main subspecies of carp:

1. Mirror.
2. Scaly.
3. Naked.

These subspecies branch into many breeds. There are ornamental types of carp (for example, Koi carp) that are bred for aesthetic purposes.

Habitat

Carp are mainly bred in private ponds or stakes. Young carp are as unpretentious as adults. Cages - frames on which a net is stretched - are lowered into a pond with stagnant or low-flowing water. And fish live and reproduce in them.

The optimal depth of a pond for keeping carp is one and a half to two meters. The shallow depth allows for good water heating. It is recommended to install lighting to saturate the reservoir with oxygen and lighting for the dark. Night lighting will attract insects, which the carp feed on.

With a balanced menu and proper care, a small carp weighing 30 grams gains weight three times per season. And by October his weight is up to a kilogram.

White silver carp

The silver carp is best suited for living in the southern regions. This fish eats an amount of food equal to half its weight per day. Thanks to this innate gluttony, the weight of silver carp can reach twenty kilograms.

It gets along well with other herbivorous fish, since its diet does not compete with their menu.

The diet of silver carp is presented in the table below:

The reclamation abilities of silver carp are indispensable for eutrophic ponds. Sexual maturity in silver carp depends on climatic conditions: in the southern regions they are ready to reproduce at the age of 5 years, and in the northern regions at 8.

Bigheaded silver carp

It differs from its white counterpart in its shortened body and huge head and well-developed gill filtration apparatus.

Like white carp, bighead carp eats up to half of its own weight per day. For the first two weeks, the fry feeds on small plankton alone, and over time switches to larger algae. Adult bighead carp prefer blue-green phytoplankton.

This variety of silver carp grows the fastest; the weight of an adult fish can reach up to 40 kilograms. However, as the population increases, bighead carp compete with carp. Sexual maturity of these fish does not depend on the habitat and occurs on average at five years of age.

Fish polyculture

Currently, most fish farms have switched to intensive cultivation technology, which is called pasture-based fish farming. A characteristic feature of such fish farming is the use of several fish polycultures. Calculation of the density of planting material for various types of herbivorous fish in this case depends on:

• Natural productivity of fish.
• Mineralization of the reservoir.
• Feeding ration.
• Age of fish.
• Sizes of fish.

The ideal conditions for productive breeding of herbivorous commercial fish species, as well as for small marine fish, are rapid warming of the reservoir. This allows you to increase the temperature of the pond water to optimal values ​​- over 20° Celsius - for feeding fish. Considering the natural temperature regime, three summer months are the most suitable time for fish breeding.

Place for raising fry

Carp larvae and fry of other herbivorous fish spend their entire “childhood” in closed water supply installations (RAS) for growing fish - incubation devices that promote the growth of young animals (VNIIPRH). The density of the number of fry in a RAS for growing fish is directly proportional to their weight, and on average is about two hundred and fifty thousand larvae per cubic meter. Then the grown fry are moved into specially equipped containers - pools or trays.

Features of feeding carp and herbivorous fish

What to feed the fish? This is the main question of a caring owner interested in the growth of young animals. That is why it is so important to spend time studying the distinctive feeding characteristics of various types of herbivorous fish, their nutritional relationships, as well as time to transfer the fry to specialized food.

The starting food for the larvae and fry of herbivorous fish is the compound feed RK0SZM or its analogue - “Equizo”. The composition of this feed includes:

• Microbiosynthesis products with a high protein concentration.
• low fat content.
• Vegetable oil.
• A mixture of multivitamins.
• Wheat flour.
• Sodium caseinate.

After the weight of the young animals reaches 100 mg, they are transferred to feeding with STRAS-1 compound feed. The percentage of the composition of STRAS-1 is:

• Proteins - 55%.
• Fats - 7%.
• Carbohydrates - 16%.
• Water -10%.

For better digestibility, about 50% of the protein compounds included in the feed are destructured. The use of starter feed for fry of herbivorous fish is permitted after switching to external feeding. The frequency of feeding in incubators is from 20 minutes to half an hour. A single portion is distributed evenly in the area where the fry gather. It is recommended to feed the larvae only during the daytime.

Compound feed RK-SMZ, Equizo and STRAS-1 are developed for feeding fry in the absence of natural food. To adapt the fry to their natural habitat, it is necessary to add small forms of phytoplankton to incubators with fish. The presence of even small quantities of living phytoplankton in the diet of young animals ensures rapid growth of fry and improvement of their vital signs.

The diet of carp larvae weighing up to fifty grams consists of special feed AK-1KE. It includes:

• Meat and bone meal.
• Yeast.
• Vegetable oil.
• A mixture of multivitamins.
• Dicalcium phosphate.

Once the carp fry reaches a weight of fifty grams or more, it is transferred to AK-2KE compound feed. And when gaining weight from two hundred grams - RGM feed - 2KE. All feed for carp fry includes dry mixtures of natural origin.

The daily allowance for carp fry, weighing up to twenty grams, is distributed evenly and is given every hour during daylight hours. When carp fry gain a weight of twenty grams or more, the number of feedings per day is reduced to nine to ten times.

In winter, if the water temperature remains 6°C or higher, the fish continue to be fed, dividing the daily intake into three meals. In winter, feeding is carried out only during the daytime and in an amount sufficient to maintain metabolic processes. So:

• If the water temperature is 6-8°C, the daily food intake is 0.5% of the weight of the fish.
• If 9-10°C - the norm is up to 1%.
• If 10-12 °C - the norm is up to 2%.

Vegetable feed with a reduced protein content is best suited for feeding herbivorous fish in winter.

Planting of carp fry, whose weight does not exceed twenty grams, is carried out at a density of:

• For swimming pools 650 units per cubic meter.
• In cages - up to 500 units per cubic meter.

For young large fish species, this amount does not exceed 250 individuals per cubic meter.

Fish farm: business plan

Fish farming is not a new business idea, but its relevance today is only increasing. The option of maintaining your own pond or pond is a profitable business. But at the initial stage it requires substantial investments and competent organization of the process.

First, you should find a plot of land suitable for installing a pool with cages. A prerequisite for successful fish production is the presence of a special filter and equipment necessary for a particular breed of fish.

Purchasing young animals will also require significant financial costs. Keep in mind that the price of larvae is higher than that of grown individuals. It is also necessary to calculate the natural losses of the fry during the rearing process. On average, this amount is up to 10%. It will be possible to raise a full-fledged adult from a fry only after two to two and a half years.

Any business project begins with drawing up a business plan. An assessment of the fish market makes it possible to conclude that carp is the most popular product on fish counters.

Estimated estimate for organizing a fish farm for growing carp:

• Purchase of carp fry for replanting in cages - about ten thousand rubles;
• The salary of farm employees is thirty thousand rubles;
• A batch of feed for carp larvae and a vitamin mixture - seven to eight thousand rubles;
• Other expenses (payment of water, electricity, gas for heating the pool) - twenty to twenty-five thousand rubles.

In total, the approximate amount you need to have to start a fish farm is about seventy thousand in national currency. Therefore, a fish farm is classified as a business with an investment category of up to one hundred thousand rubles. For the northern regions of Russia, this amount increases significantly and amounts to approximately five hundred thousand.

As for profit, without deducting taxes and fees, it ranges from one hundred thirty to one hundred and fifty rubles. However, you can count on profit no earlier than in two to two and a half years. By this time, the carp fry turns into an adult and its weight is one to two kilograms.

Carp, like no other species, is suitable for organizing a fish farming business. This is due to its unpretentiousness in food and maintenance. And the rapid growth of carp fry will help you quickly recoup costs and generate income. However, you should not neglect the quality of conditions for keeping fish and feed. Consumerism can lead to the development of pathologies in fry and their death, as well as non-compliance of adult carp meat with sanitary standards.

Pros and cons of the fishing business

If we analyze the successful experience of fish farming, we can highlight the following advantages in favor of this area of ​​agriculture:

Of course, in every barrel of honey there is a fly in the ointment. Running a business for growing herbivorous fish has its pitfalls:

• Seasonality of product sales. Basically, the fry gains marketable weight by the fall, and the massive arrival of fish on commodity shelves, accordingly, leads to a decrease in price.
• During the summer, transporting and storing fish is a very costly and complex undertaking.
• The growth of fish is also directly dependent on the time of year: in the warm season, carp actively feeds and grows quickly, in cold weather these indicators decrease;
• Not every retail outlet can afford to purchase equipment for keeping the fish they sell.
• A separate expense item falls on maintaining sanitary standards, treating fish and protecting them (we have a lot of people who want to go “free fishing”).

To get additional profit on a fish farm, it is necessary to take into account the natural symbiosis of the bred polyculture. There is an option for breeding crayfish in the same area as carp. Go for other types of herbivorous fish. Lake crayfish not only perfectly clean the bottom of a reservoir (pond, cages), but they themselves are a competing product. There is no need to feed the crayfish additionally. They feed on leftover fish food and eat phytoplankton. During the molting period, crayfish become weak, some of them die, becoming food for fish.

It is possible to breed carp larvae for sale. To keep such fry, a separate water area will be required. However, such additional income is not possible immediately: male carp reach sexual maturity by the third year of life, and females only by the fifth.

Israeli experience

A fish farm has appeared in the middle of the sands in Israel. The distance to the nearest body of water is about three hundred kilometers, while the density of farmed fish per cubic meter of water is about one hundred kilograms.

To create a water space on the farm, a well about a kilometer deep was needed, from where water comes, whose chemical composition corresponds to sea or ocean water. This allowed the owners to introduce and successfully reproduce small sea fish.

Of course, the life support of the fish of the desert farm is in the hands of the employees of a special laboratory. They monitor the composition of the water, the operation of the fans, the purification and distillation of water and its saturation with oxygen. In addition, the life of fish also depends on uninterrupted electricity.

The creation of such a fish farm is not just a breakthrough in the development of desert territory. Such a fishing enterprise creates jobs and an alternative to fishing at sea.

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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 quantities 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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No matter how much you might like it, a pond with plants cannot accommodate a whole range of fish. The reason is clear and quite respectful: these fish consider any plant as a source of food. These species include large cichlid fish, especially Central American fish, as well as tilapia and their relatives. These fish dig up any plant and eat it. The same can be said about cichlids from the African Great Lakes: these beautiful, brightly colored fish are incompatible with plants, since they are not at all averse to eating them. In nature, many species of these fish feed exclusively on algal fouling from stones. In addition, these cichlids need slightly alkaline water with special parameters, which is completely unsuitable for plants.

Goldfish, so beloved by beginning aquarists, are also on the list of pests: they constantly rummage at the bottom, dig up plants, and always chew soft leaves. For the same reason, there cannot be large catfish in an aquarium with thickets. They prefer plants for daytime shelters and dig deep beds in their roots. The pectoral fins of many catfish are armed with a strong, barbed ray. With this “saw” the fish injures the leaves of plants and can even cut off the strong petiole of Echinodorus.

There are herbivorous fish among representatives of other taxa. South American Abramites from the Anostomidae family look very impressive: a wide diamond-shaped body decorated with wide coffee stripes, a tiny mouth at the end of a narrow head, and most importantly, these fish swim head down. Such funny fish just beg to be added to the aquarium. But you can afford this with big reservations. You can’t even imagine that in just 15 minutes a couple of abramites can deal with a large group of plants. Despite their tiny mouth, the fish very quickly bite off the edge of the leaf blade and gnaw the thickets like caterpillars. Abramites even have their own list of delicacies: the most delicious for them is Hygrophila polysperma, followed by other species of this plant, Vallisneria, and narrow-leaved Echinodorus.

But Abramites almost does not touch Cryptocorynes. The reason is that this plant has a caustic juice, and after trying its leaves several times, Abramites later refuse this plant. There is no doubt that the fish first try cryptocoryne: when they see it, they try to bite off a piece (tooth marks are clearly visible along the edges of the leaf). I decided to find out what the striped beauties didn’t like so much, and chewed a small leaf. The juice of the plant is quite insidious: at first it does not seem pungent, and only after a few minutes a slight but unpleasant burning sensation spreads in the mouth. I advise you to repeat my experience with great caution: cryptocorynes, like all representatives of the aroid family, are toxic, their juice can be poisoned.

Unlike their small relatives, which provide benefits to plant growers, large chain catfish also love to feast on juicy soft leaves. Therefore, pterygoplichthys, panaka, glyptoperichthys, hypostomus and lipozarcus are not allowed into the decorative pond.

I. Sheremetyev

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