No matter how much you want, but in a pond with plants, a whole number of fish cannot be settled. 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, because they are not averse to feasting on 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, completely unsuitable for plants.

Goldfish, so beloved by novice aquarists, are also on the list of pests: they constantly dig at the bottom, dig up plants, and always chew on soft leaves. For the same reason, large catfish cannot be in an aquarium with thickets. They choose plants for daytime shelters, dig deep beds in their roots. The pectoral fins of many catfish are armed with a strong prickly ray, on which notches are applied. 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 (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 ask for an aquarium. But you can afford it with big reservations. You can’t even imagine that in just 15 minutes a pair of abramites is able to deal with a large group of plants. Despite the 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 hygrophila multi-seeded is the most delicious for them, followed by other species of this plant, vallisneria, narrow-leaved echinodorus.

But Abramites almost do not touch Cryptocorynes. The reason is that this plant has a caustic juice, and after tasting their leaves several times, abramytes 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 (the teeth marks are clearly visible along the edges of the leaf). I decided to find out what the striped beauties did not like so much, and chewed on a small leaf. The juice of the plant is rather insidious: at first it does not seem caustic, 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 benefit crop growers, large chain catfish also love to feast on juicy soft leaves. Therefore, pterygoplichthys, panaki, glyptoperichthys, hypostomus and lipozarkus are not allowed in a decorative pond.

I. Sheremetiev

Therefore, mature individuals have a significant weight, which attracts fish farmers. In addition, white is specially bred in and -coolers of power plants, as it cleans them of unnecessary vegetation. This fish eats not only aquatic vegetation, but also vegetation on the banks of rivers, and also does not disdain peeling vegetables, cabbage leaves, potato skins. Cupid is even able to jump out of the water to grab a branch of a plant they like with their teeth. Together with an increase in their own weight, cupid and silver carp improve the hydrological regime of rivers and lakes. In addition, these fish are resistant to infectious diseases, undemanding to the conditions of detention. Herbivorous fish winters at the bottom of the pits. At a water temperature of +10 degrees C, phytophages stop feeding, and at a temperature of +5 degrees C they turn off altogether, stop responding even to external stimuli. The only danger of breeding phytophages in water bodies is that they are able to destroy all vegetation in a pond or lake and disturb thus ecological balance. Artificial breeding of phytophagous fish has become popular and profitable for some time now. They are bred in ponds along with carp, planting juveniles of carp and silver carp there. There are also aquarium phytophagous fish. These are everyone's favorite goldfish, large cichlid fish. They also feed on plants, so you need to carefully populate the aquarium with them. In addition, some species of cichlid fish feed on fouling from stones and require special alkalized water, which is unacceptable for other fish. Some fish, catfish, are specially planted in the aquarium to clean it. But other types of phytophages, beautiful abramytes, for example, are capable of destroying the entire flora of the aquarium in a few minutes.

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Advice 2: Why predominantly herbivorous fish are bred

Herbivorous fish, or phytophages (from the words "phyto" - a plant and "phage" - a devourer), can be found in any body of water on our planet, except, perhaps, Lake Baikal. Representatives of this group are also bred in home aquariums. What is their popularity?

Fish are usually divided into several groups: animal-eating (predatory) and omnivorous. Herbivores, based on, include fish that feed on various parts of aquatic plants.

In order to understand that in fish farming, it is the breeding of herbivorous fish that is given priority, we will arrange all the inhabitants of the reservoir according to the nature of their food. The result is a food chain, each link of which is food for the next. The food chain of a reservoir looks like this: plants - invertebrates - fish. It is phytophages that are the end product of the shortest food chain of any reservoir: algae - fish.

For comparison, the food chain for fish looks like this: algae - invertebrates - benthos (organisms that live on the bottom or in the ground) - small fish - predatory fish. If we take into account that with an extended food chain, the energy costs for obtaining the final product (fish) increase many times, it becomes clear that breeding herbivorous fish is energetically more profitable. In addition, phytophages grow much faster than predatory ones, which means they are more actively used for breeding.

Unlike industrial fish farming, there is no doubt about the interest in breeding herbivorous fish for aquariums and ornamental ponds. This is their attractive appearance. But in the case of ornamental fish, their love of plants is more of a disadvantage. Indeed, when designing an aquarium or reservoir, it should be borne in mind that these fish consider any plant as a source of food. In addition, herbivorous fish feed little by little, but often. They need food after 2-3 hours, and by morning they are very hungry.

Sources:

• herbivorous fish in 2018

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

The pond rearing cycle for carp and other herbivorous fish traditionally takes two to three years. Feeding herbivorous fish in the ponds is carried out by breeding polyculture and fertilizing the ponds. The rejection of the use of artificial feed with mineral fertilizers allows you to get an annual increase in all types of ponds (nursery and feeding).

Types of herbivorous fish

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

• The silver carp is white and variegated.
• Carp.
• White amur.

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

White amur

This belongs to the carp family and is characterized by rapid growth. There are known cases of weight gain by grass carp up to 50 kg. Any vegetation of reservoirs, meadow grasses, as well as concentrate feed is suitable for feeding cupid. The diet of white 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 him pass through the intestines of the fish and again find themselves in the reservoir, creating comfortable conditions for other fish to live and reproduce. The number of reclamation fish depends on how much the pond is overgrown with algae and ranges from one hundred to five hundred units of grass carp per hectare.

To increase productivity, it is recommended to introduce feed from perennial grasses into the fish diet. Alfalfa or sainfoin will do. With low vegetation in the pond, grass carp can feed on mixed fodder for some time. But they should not be abused. This can lead to the development of serious pathologies in the population.

Readiness for reproduction in white 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.

With the help of replanting grass carp in the amount of up to 600 pieces per 1 hectare, it is possible to clean poorly overgrown reservoirs. For moderately and heavily overgrown ponds, the number of grass carp should be increased to a thousand individuals per hectare. The introduction of young grass carp helps to clear unprofitable water bodies overgrown with reeds in one vegetative period and prepare them for growing carp fry.

But in order for grass carp to prove itself as a reclamator of a water area, 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 successful wintering. And to ensure the heating of water in the summer months up to 18 ° C.

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

This technology has been successfully used by the Saratov fish hatchery for herbivorous fish for a long time. After replanting two-year-old and three-year-old grass carp, the enterprise managed to get rid of algae and reeds on an area of ​​more than 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 of the bony fish is herbivorous. In fact, carp is a tamed carp. characteristic feature his digestive system is the absence of a stomach. Therefore, the carp devotes its entire life to finding food. Fortunately, it is unpretentious in food - the carp absorbs algae and other aquatic vegetation, insect larvae, midges and small plankton with equal pleasure.

Carp is a long-lived fish, it can live for about half a century. Of course, it makes no sense to engage in the cultivation of carps for such a long period of time.

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

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

There are three main subspecies of carp:

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

These subspecies branch out into many breeds. Exist decorative types carp (e.g. koi carp), which are bred for aesthetic purposes.

Habitat

Mostly carp are bred in private ponds or rates. Carp fry are as unpretentious as adults. Cages are lowered into a pond with stagnant or low-flowing water - frames on which a mesh is stretched. And fish live and breed in them.

The optimal depth of the pond for keeping carp is one and a half to two meters. A shallow depth contributes to a good heating of the water. It is recommended to install to saturate the reservoir with oxygen and backlight for the dark time of the day. Night lighting will attract insects, what the carp eats.

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

Silver carp white

Best of all, the white silver carp is adapted for living in the southern regions. In a day, this fish eats an amount of food equal to half its mass. Thanks to such congenital gluttony, the weight of a white carp can reach twenty kilograms.

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

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

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

bighead carp motley

It differs from its white counterpart in a shortened body and a huge head and a well-developed filtration apparatus of the gills.

Like white, bighead carp eats up to half of its own weight per day. For the first two weeks, the fry feeds on one small plankton, eventually moving on to larger algae. Adult bighead carps prefer blue-green phytoplankton.

This species of silver carp grows the fastest, the weight of an adult fish can reach up to 40 kilograms. However, with an increase in population, bighead carps compete with carps. The sexual maturity of these fish does not depend on the habitat and falls on average at the age of five.

Fish polyculture

At the moment, most fish farms have switched to intensive rearing technology, which is called pasture fish farming. A characteristic feature of such fish rearing is the use of several fish polycultures. Calculation of the density of planting material various kinds herbivorous fish in this case depends on:

• Natural productivity of fish.
• Mineralization of the reservoir.
• Feeding ration.
• The age of the fish.
• Fish sizes.

Ideal conditions for the productive breeding of herbivorous species of commercial fish, as well as for small sea ​​fish, is the rapid warming of the reservoir. This allows you to increase the temperature of the pond water to the optimum values ​​- over 20 ° Celsius - for feeding fish. Given the natural temperature regime, three summer months is the most suitable time for fish breeding.

Place to grow fry

Carp larvae and fry of other herbivorous fish spend their entire “childhood” in recirculating water supply systems (RAS) for growing fish - incubation devices that promote the growth of young animals (VNIIPRKh). The density of the number of fry in a RAS for growing fish is directly proportional to their mass, and on average is about two hundred and fifty thousand larvae per one cubic meter. Then the grown fry are transferred to 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's why it's so important to take the time to study distinctive features feeding of various types of herbivorous fish, their nutritional relationships, as well as the time for transferring fry to specialized food.

The starting food for larvae and fry of herbivorous fish is RK0SZM compound feed or its equivalent - "Ekvizo". The composition of this feed includes:

• Products of microbiosynthesis with a high concentration of protein.
• reduced fat content.
• Vegetable oil.
• Multivitamin blend.
• 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:

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

For better digestibility, about 50% of the protein compounds that make up the feed are destructured. The use of starter feed for fry of herbivorous fish is allowed 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 of ​​fry accumulation. It is recommended to feed the larvae only during the daytime.

Compound feed RK-SMZ, "Ekvizo" and STRAS-1 are designed 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 amounts of live phytoplankton in the diet of young animals ensures the rapid growth of fry and the improvement of their vital signs.

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

• Meat meal.
• Yeast.
• Vegetable oil.
• Multivitamin blend.
• Dicalcium phosphate.

Upon reaching the carp fry of a weight of fifty grams or more, it is transferred to the AK-2KE compound feed. And when gaining weight from two hundred grams - feed RGM - 2KE. The composition of all compound feeds for carp fry includes dry mixtures of natural origin.

The daily norm for carp fry, weighing up to twenty grams, is distributed evenly and is given out 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.

Weight of young carp (g)	Degree of water heating (°С)

IN winter period, if the water temperature is maintained at 6°C and above, the fish continue to be fed, distributing daily allowance for three doses. In winter, feeding is carried out only in the daytime and in an amount sufficient to maintain metabolic processes. So:

• If the water temperature is 6-8°C - the norm of food per day 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%.

It is best to feed herbivorous fish in winter with vegetable compound feed with a low protein content.

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

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

For young animals large breeds fish, this number does not exceed 250 individuals per cubic meter.

Fish farm business plan

Fish breeding is not a new business idea, but its relevance is only increasing today. The option of keeping your own bet or pond is a profitable business. But on initial stage requires a solid investment and competent organization of the process.

To begin with, it is worth finding a plot of land suitable for installing a pool with cages. A prerequisite successful production fish is the presence of a special filter and equipment required for a particular breed of fish.

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

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

Estimated estimate for the organization of a fish farm for growing carp:

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

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

As for profit, without deducting taxes and fees, it ranges from one hundred and thirty to one hundred and fifty rubles. However, you can count on profit not earlier than in two or 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 variety, is suitable for organizing a fish farming business. This is due to its unpretentiousness in food and maintenance. And the fast growing carp fry will help to quickly recoup the costs and get income. However, it is not worth neglecting the quality of the conditions for keeping fish and feed. The consumer attitude can lead to the development of pathologies in the fry and its death, as well as the discrepancy between the meat of adult carps and sanitary standards.

Pros and cons of the fishing business

If we analyze the successful experience of fisheries management, 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 own "pitfalls":

• Seasonality of product sales. Basically, the fry is gaining commercial weight by autumn, and the massive supply of fish to the commodity counters, respectively, leads to a decrease in prices.
• IN summer period Transportation and storage of 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 feed and grow rapidly, in the cold these figures decrease;
• Not every retail outlet can afford to purchase equipment for keeping the fish they sell.
• A separate item of expenditure falls on the maintenance of sanitary standards, the treatment of fish and their protection (we have many who want to go on "free fishing").

In order to get additional profit on a fish farm, it is necessary to take into account the natural symbiosis of the cultivated polyculture. There is an option to breed crayfish in the same area as carps. Go with other types of herbivorous fish. Lake crayfish not only perfectly clean the bottom of the reservoir (pond, cages), but are themselves a competing product. You don't need to feed the crayfish. They feed on the remains of 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. For the maintenance of such fry, a separate water area will be required. However, such additional income is not immediately possible: male carps reach puberty 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 reservoir is about three hundred kilometers, while the density of fish grown per cubic meter of water is about one hundred kilograms.

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

Of course, the life support of the desert farm fish is in the hands of the staff of a special laboratory. They monitor the composition of water, the operation of 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 the desert. Such a fish enterprise creates jobs and an alternative to catching fish in the sea.

Introduction

At present, due to the growing influence of anthropogenic factors on the ecosystem of water bodies, the number of populations of valuable commercial fish species is drastically reduced, the reproductive capacity of populations cannot ensure the replenishment of natural stocks in water bodies, therefore one of the ways to solve this problem is artificial reproduction. Much attention is paid to the improvement of fish breeding technology, which in turn will have a positive impact on the number of many fish species. Fish breeding enterprises are engaged in breeding commercial fish species, obtaining viable juveniles and releasing them for feeding in natural reservoirs. These enterprises are located in all fishing reservoirs and basins.

Such valuable commercial fish are herbivorous fish, which are of great importance in the development of the country's fisheries, as well as environmental significance, which lies in their use as biological (ecological) ameliorators. This value will increase in the future. The dramatic increase in fish production provided by herbivorous fish is revitalizing the economy. The effectiveness and expediency of the fight against pollution of water bodies coincides with the interests of the struggle for the purity of natural waters. These fish are the most effective means of restoring and stabilizing the biota of water bodies.

Far Eastern herbivorous fish (silver carp and bighead carp, grass carp) have long attracted the attention of fish farmers as highly productive objects, since their value as aquaculture objects lies primarily in their nutritional characteristics. These fish directly use the primary production formed in the reservoir (algae, higher aquatic plants), which makes it possible to obtain marketable products already at the second link in the trophic chain. In the country, herbivorous fish provide about 25% of the production of pond farms, and in the southern regions 50-70%.

Far Eastern herbivorous fish play an important role in solving the problem rational use natural resources of inland waters of the country. Annually in our country about

1.5 billion larvae of these fish.

The central issue in solving the problem of increasing the production of planting material for grass carp and silver carp is the development of scientifically based methods for the formation and operation of broodstock. At present, the most favorable areas for growing these objects have been identified, the main methods of biotechnology have been worked out, the features of development, as well as the influence of environmental factors, have been studied.

The most favorable area for breeding white and motley silver carp, grass carp is the Pacific region, in particular, the river. Cupid, as here are the most suitable conditions for their cultivation. It is more expedient to use sires of Amur and Chinese origin as initial lines, such organization of breeding allows increasing the survival rate of underyearlings by 15–20%.

When working with herbivorous fish, spawners are obtained by catching from water bodies. When using such reservoirs, it is necessary to control the genetic purity of the planting material, as well as to monitor the physiological state of the fish. The ability to control the main environmental factors that determine the growth and development of fish, obtaining reproductive products in optimal timing, create prospects for organizing the reproduction of herbivorous fish.

On the Amur River there are Anyuysky, Bidzhansky, Gursky fish hatcheries, which are under the jurisdiction of the FGU "Amurrybvod", as well as the Luchegorsk fish hatchery station of the TINRO-Center for the production of planting material for herbivorous fish. Their total production capacity is 64 million copies. juveniles. Industrial return coefficient in r. Cupid made up 1%. A feature of the Amur fish hatcheries is their remoteness from the Amur Estuary.

In 1952-1961. catches of herbivorous fish in the basin of the river. Amur made up 37.1-70.8% of the total catches, while at present the catches of these fish have significantly decreased and amounted to only 7.1-22.4%.

A surge of interest in the breeding of grass carp, white and bighead carp was felt by the employees of the Luchegorsk fish breeding station of the TINRO Center several years ago. Then the first commodity farms appeared in the region. The growth of orders for larvae and juveniles of herbivorous fish is increasing every year. Indeed, in the south of the Far East region, only at the fish breeding station of the TINRO Center, broodstocks of the Amur carp, German framed carp, colored Japanese carp, white and motley silver carps and grass carp have been preserved. This is a typical set of several species and breeds of heat-loving cyprinids that can be successfully grown in lakes, reservoirs, ponds and pools on household plots, increasing their production to several tens, and then hundreds of thousands. In 2008, about 80 organizations and individuals ordered fish seed, and requests continue to come in. Several million juveniles and herbivorous fish have already been sold this year. But the possibilities for growing planting material of various sizes at the Luchegorsk station are limited due to the lack of space for cages.

Therefore, the construction of a fish hatchery in the Amur region is necessary to increase the stocks of herbivorous fish.

This term paper is the justification for the construction of a fish hatchery on the Amur River for the reproduction of herbivorous fish (white carp, white and bighead carp) with a capacity of 20 million.

Chapter 1

white carp / Hypophthalmichthys molitrix / - a schooling freshwater pelagic fish that feeds on small floating algae throughout its life (except for the earliest ones). The main systematic features are: rather high body, covered with very small scales; the head is wide; the eyes are located below the axis of the body (Fig. 1) (Vasilyeva, 2004).

The silver carp has a number of morphological adaptations for feeding on phytoplankton. Thin, closely spaced gill rakers are interconnected by transverse bridges, forming a "sieve" that allows you to strain out small forms of algae and zooplankton. The algae retained by the gill mesh are compressed in a lump due to the interaction of the pharyngeal teeth strongly compressed from the sides, covered instead of enamel with a cornea, and a millstone covered with a soft mucous membrane. Food in a compressed form enters the intestine, the length of which in an adult silver carp exceeds the body length by 10-13 times (Russ, 1983).

The nutritional features of the white carp are determined by the structure of the filtration apparatus, as well as the composition and size of food organisms in the reservoir. The silver carp feeds mainly on phytoplankton and detritus. It switches to feeding on phytoplankton at a length of 1.5 cm, and before that it feeds mainly on zooplankton. All groups of algae are found in its food, however, there is a certain selectivity in relation to various groups and types of algae. It prefers diatoms and green algae, but can also feed effectively on blue-green algae, including macrocystis, a form that causes water blooms in reservoirs. The share of detritus in the diet of silver carp is 90% (Ponomarev, 2008).

Rice. 1 Appearance of white carp

Silver carp is a valuable herbivorous fish. It reaches a length of 1 m and a mass of 16-18 kg. The age limit is over 20 years. The length of silver carp in commercial catches is from 20 to 75 cm, weight is from 120 g to 5.6 kg, on average 41 cm and 1.2 kg.

The area of ​​natural habitat of the silver carp extends from the Amur basin to South China. In Russia, it is distributed in the middle and lower reaches of the Amur (from the mouth of the Kumara River to the mouth of the Amgun), including in large lakes - Orel, Qatar, Bolon. It occurs in the Sungari, the lower reaches of the Zeya, Ussuri, in the lake. Khanka. Recently discovered on Sakhalin (Safronov and Nikiforov, 1995). As an object of fish farming, it is widely settled in the countries of Asia and Europe. Introduced into many water bodies of Russia and the republics of the former USSR: reservoirs and the lower reaches of the Volga, Dnieper, Dniester, Prut, Don, Kuban, Terek, the Aral Sea basin, Lake. Balkhash and others, where in some cases natural spawning is observed. As an object of fish farming, it is grown in many ponds and reservoirs - the territory of the country.

Figure 2 shows the habitats of the silver carp in Central Asia and Europe.

Fig. 2 Distribution of white carp

In summer, the silver carp feeds mainly in the Amur channels and lakes. For the winter, it moves to the Amur bed, where it lies in pits. The time to reach puberty is determined primarily by the geographical latitude of the reservoir. The silver carp becomes sexually mature only at the age of 7-8 years, reaching a mass of about 4 kg. Males usually mature a year earlier than females. Spawns at sharp rises in water level, spawning pelagic eggs. In the Amur, the main spawning grounds are located in the area from Khabarovsk and above. Spawning time - early June-mid-July.

Absolute fecundity from 100 to 1500 thousand pieces. eggs, the working fecundity of females is about 500-700 thousand eggs. Spawning is portioned (up to three portions), at a water temperature of 25 ° C, development continues for about 2 days. After swelling, the size of the eggs increases in diameter up to 5 mm. Embryonic development in natural conditions of the river. Cupid is carried out in the water column.

The hatched prelarvae are 5 mm long. Prelarvae in the water column are passively carried downstream. After about 3-4 days at a water temperature of 20 - 23 0 C, the hatched larvae switch to a mixed diet and begin to actively swim. The larval period begins at the age of 7 days with a length of 6-8 mm (Nikolsky, 1974). In other water bodies (China, Tsimlyansk reservoir) only one portion of caviar can be spawned. Usually, spawning takes place in the early morning hours and is very violent, spawners jump out of the water (Reshetnikov, 2002).

Bighead carp / Aristichthys nobilis / - similar in body shape to a white carp , but has a larger head, the eyes are set more widely, the body is less high, the pectoral and ventral fins, as well as the caudal peduncle are longer. The coloration is much darker, on the sides of the body in adult fish dark spots(Fig. 3).

Rice. 3 Appearance of bighead carp

Bighead carp is a Chinese species, distributed in the rivers of Central and South China. Previously, it was not recorded in the Amur (Nikolsky, 1974). It got into this basin in the late 1950s from a number of Chinese fish farms located in the Songhua basin as a result of catastrophic floods. Subsequently, it spread widely along the Amur, where it occurs from Blagoveshchensk to the Amur Estuary. There are in Ussuri and lake. Khanka. It occurs in small quantities in the lower reaches of the Zeya and Amgun. It is widely acclimatized in the European part of Russia (delta and reservoirs of the Volga, lower reaches and reservoirs of the Dnieper, Prut and Danube reservoirs, Dniester, Kuban, Don, Terek, Amu Darya, Syr Darya, Balkhash - Ili basin, etc.). As an object of aquaculture on the warm waters of the state district power station, nuclear power plant, thermal power plant, it is grown much further north (Verigin, 1979).

Figure 4 shows the habitats of the bighead carp.

Rice. 4 Distribution of bighead carp

This is a large fish, up to 146 cm long and weighing up to 32 kg. Under the conditions of Turkmenistan, it reaches a mass of over 50 kg; in Cuba, individual specimens of bighead carp weighed 60 kg. By way of life, heat-loving fish. The main food object is zooplankton, but by autumn the proportion of phytoplankton, including blue-green algae, increases in the intestines. Due to the nature of nutrition, the intestines of the bighead carp are shorter than those of the white one.

It matures in different reservoirs in different ages: In Turkmenistan it becomes sexually mature at 4 years old, in Moldova - at 4-6 years old, in India at 2 years old, in Cuba at 2-3 years old, in the Moscow region at the 5th year of life. Spawns during periods of a sharp rise in water level, at the end of May. Absolute fecundity 629-1 million. eggs. Optimum temperatures for caviar development are 16.5 -21 0 С.

The bighead carp is a valuable commercial fish. The quality of the meat is higher than that of the silver carp. It is a promising object of pond and warm-water cultivation.

White amur/ Ctenopharyngodon idella / - has an elongated, valky, runaway body, covered with thick scales. It crushes food with powerful sawtooth teeth located on the mandibular bones. The mouth is semi-inferior, the forehead is very wide (Vasiliev, 1985) (Fig. 5).

Rice. 5 Appearance of grass carp

The natural habitat is East Asia (China) from the Amur south to Xijiang. In Russia, it occurs in the middle and lower reaches of the Amur (up to Blagoveshchensk), in the mouths of the Sungari, Ussuri and Lake Khanka. It is widely introduced into water bodies of Europe, Asia and North America as an object of fish farming. For the purpose of acclimatization, it was released into many water bodies of Russia (systems of the Dnieper, Don, Volga, Kuban, Ural, Amu Darya, Syr Darya, Lake Balkhash).

The habitat of white carp is shown in Figure 6.

Rice. 6 Spread of grass carp

White carp is characterized by rapid growth, in the Amur basin it reaches a length of 1.2 m and a weight of 40-50 kg. Yearlings in natural conditions have a length of 20 - 25 cm and a mass of up to 600 g, after 2 years the mass of grass carp reaches 2.4-3 kg. The fastest growth was recorded in the tropical zone, where two-year-olds can reach a weight of 14 kg (Bagrov, 1985).

Makes seasonal migrations. In the summer, it feeds in the adnexal system, in the winter it goes into the riverbed and keeps on the pits.

Young carp consume zooplankton (crustaceans, rotifers, chironomids), adult fish are narrow stenophages, feeding mainly on higher aquatic vegetation (including terrestrial, flooded with summer monsoon floods), grinding it with jagged pharyngeal teeth. In the south of Russia, grass carp also uses hard vegetation (reed, cattail) for food. At the same time, he willingly consumes terrestrial plants (clover, alfalfa, cereals).

In the Amur basin it becomes sexually mature at the age of 9-10 years with a length of 68-75 cm, in the rivers of China - 1-2 years earlier, in Cuba they mature at the age of one, females a year later. Daily ration, growth rate, puberty depend on water temperature. Spawns portions of pelagic caviar. Fertility in females ranges from 237 to 1686 thousand, averaging 800 thousand eggs. Spawning is portioned, strongly stretched from April to August at a temperature of 23-28 0 C, the main spawning grounds are located in the Songhua River. Caviar usually spawns in the upper layers of the water during the period of sudden rises in the level caused by heavy rains. Fertilized grass carp eggs are bathypelagic, their specific gravity is somewhat heavier than water, and is sensitive to water quality and to the content of dissolved oxygen in it. The incubation period lasts 18-72 hours. The hatching of the larvae occurs after about 3 days with a length of 6.9 mm. Subsequently, the larvae migrate to the coastal zone and shallow bays, having reached a length of 2.5–3 cm, they switch to consumption of vegetation.

The development of herbivorous fish is divided into embryonic, larval, and juvenile periods.

The eggs are pelagic, transparent, 3.5 - 4.5 mm in diameter. The egg shell is represented by only one primary (proper) shell - the radiant zone.

The embryonic period includes 8 stages of 22 stages.

I stage. Hydration of the cavity between the egg membrane and the egg (the appearance of the perivitelline space) and the formation of a blastodisc (1-3 stages).

II stage. Cleavage of the blastodisc from two blastomeres up to and including the blastula. In this case, predominantly quantitative changes occur: an increase in cells and a decrease in their size (4-10 stages).

III stage. Gastrulation is the formation of germ layers. It is accompanied by fouling of the yolk sac with blastoderm (stages 11-13).

IV stage. Organogenesis - differentiation of germ layers into the rudiments of the main organs ( nervous system, chord, muscles, intestines, eyes, auditory vesicles, etc.) (stages 14-15).

V stage. Separation of the tail section of the embryo from the yolk sac, the beginning of the mobility of the body of the embryo (stages 16-18).

VI stage. Hatching of the embryo from the shell (stage 19).

VII stage. The appearance of a developed embryonic vascular system (stage 20).

VIII stage. The appearance of a mobile gill-jaw apparatus and the beginning of the functioning of the gills (stages 21-22).

The larval period includes 5 stages, 8 stages.

I stage. Mixed endogenous-exogenous nutrition of the larva (stages 23-24).

II stage. The nutrition of the larva is exclusively external - exogenous (stage 25).

III stage. Formation of unpaired fins (stage 26).

IV stage. The appearance of the second section of the swim bladder and the laying of the ventral fins (stage 28).

V stage. The formation of fin rays in paired - pectoral and ventral fins (29-30 stages).

The juvenile period includes 2 stages.

I stage. Start laying scales.

II stage. Malek with developed scaly cover.

Chapter 2

The source of water supply for the planned fish hatchery for the reproduction of herbivorous fish is the Amur River, which is formed by the confluence of Shilka and Argun and is divided into 3 parts - the upper (up to the mouth of the Zeya), the middle (up to the confluence of the Ussuri) and the lower (up to the Amur Estuary). In the upper section of the Amur bank, they are high, overgrown with forest; below the mouth of the Zeya, the Amur flows through the lowlands and, after the confluence of the Bureya, again acquires a mountainous character. Coming out of the mountain gorges, the river expands, forming channels and islands. After the confluence of the Ussuri, the wide Amur flows through a hilly, sometimes swampy lowland. When it flows into the Tatar Bay, the river forms an estuary in which the Amur has an underwater delta. The Amur River basin is located in the temperate latitudes of East Asia.

Within the Amur basin, there are four physical-geographical zones: forest (with subzones of coniferous-deciduous forests, middle and southern taiga), forest-steppe, steppe and semi-desert (with the northern subzone of semi-deserts and the subzone of dry steppes).

The length of the Amur is 2824 km, the basin area is 1,855,000 km 2 , the height of the source is 304 m, and the water discharge is 11,400 m 3 /s.

The Amur is fed mainly by rains, which account for up to 64% of the annual runoff, snow cover accounts for 19% of the runoff, and groundwater accounts for 17%. There is no clearly expressed spring flood in the Amur, and the river has its maximum levels during the summer monsoon rains. Amur is under the ice from November to the end of April - beginning of May. Level fluctuations in the riverbed relative to the low water range from 10-15 meters in the upper and middle, and up to 6-8 in the lower Amur. At the same time, during the most severe showers, spills on the middle and lower Amur can reach 10-25 kilometers and last up to 70 days.

Soils in the construction area of ​​the enterprise are floodplain and mountain-forest (brown and gray). Peat soils have deeply decomposed plant residues, have an increased ash content (from 8 to 70%), they are moderately acidic, with an average saturation of bases. With appropriate land reclamation measures, soils can be turned into arrays of fertile lands. The Middle Amur part is not yet fully used, but in terms of soil and climatic conditions it is a promising agricultural region.

River regime reflects climatic conditions region, and according to the conditions of the water regime, they are referred to the Far Eastern type with a pronounced predominance of rain runoff. The monsoonal nature of the climate determines the predominance of the summer-autumn runoff and the subordinate value of the spring runoff of most of the region's rivers.

The amount of annual precipitation ranges from 250-300 mm in the most arid southwestern part of the Amur headwaters and up to 750 mm in the southwestern part of the Sikhote-Alin ridge.

The construction of a fish hatchery is supposed to be carried out in the middle reaches of the Amur, in the area of ​​the city of Blagoveshchensk, a few kilometers from the village of Konstantinovka.

Proximity to settlements ensures the supply of labor and electricity. Automobile roads pass through the nearest villages, and a railway starts from the village of Poyarkovo, 20 kilometers from the site.

The location of the settlements and the site for the construction of the hatchery is shown in Figure 7.

Scale: in 1 cm 25 km (1:2 500 000).

Conventions:

Highway; - source of water supply;

Railway; - site for the construction of a fish hatchery

Locality

Rice. 7. Map of the location of the planned fish hatchery

The choice of the location of the fish hatchery is justified by the absence of a dam, the availability of transport routes for communication with the enterprise, the proximity of settlements (Konstantinovka, Poyarkovo, Muravyovka, Korshunovka, Nizh. Poltavka, Novoaleksandrovka, etc.), which plays an important role in providing electricity, labor. It is also important to note that in the water intake area and in the area of ​​the reservoir at a distance of 20 km Wastewater industrial and agricultural enterprises, as well as there is a sufficient amount of water suitable for the purposes of artificial reproduction.

Chapter 3 . Physico-chemical and hydrological characteristics of the source of water supply

The Amur River is a Far Eastern river with an extensive network of tributaries. The largest tributaries of the Amur are Gilchin, Dim, Curly, Bureya, Zeya, Arkhara, Uril, Belaya. And also in the Amur region there are 50 lakes with an area of ​​more than 500 hectares, the level of which is subject to sharp fluctuations throughout the year, depending on the level regime of the Amur. According to the degree of connection with the Amur, all lakes are divided into 3 groups. The first group is lakes of the floodplain type with silty soils and low-lying shores, which are closely connected with the Amur (Petropavlovskoye, Innokentievskoye, Khummi). The second group is the lakes connected with the Amur by channels (Bologne, Kizi, Kadi). The third group is lakes almost isolated from the Amur (Evoron).

Hydrological characteristic.

The Amur belongs to the rivers of predominantly rain-fed. The share of rain-fed in is from 75 to 85%, snow - from 7.5 to 22%, underground - from 2.5 to 7.5%. Due to the predominance of rain feeding, river runoff is extremely uneven throughout the year. So, in the annual runoff, winter runoff (November - March) is 3-7%, spring (April - May) - 15-20%. The largest flow is observed in the summer-autumn season and is 75-80% (Karasev, Khudyakov, 1984). . The water regime is characterized by high water in the warm season, due to heavy rains. It has a high water content, the average annual flow is 886 m 3 / s.

The climate is transitional from monsoon to continental. Monsoonity is mainly manifested in the intra-annual distribution of precipitation. On the coasts washed by the cold current, thick fogs are often observed. The amount of precipitation varies from 350 mm to 800 mm, and in summer it is 60 times more than in winter months. For 2 months, in July and August, they fall about a six-month norm.

The speed of water flow in the river is different - during the period of strong floods it reaches 3-4 m/s, in the middle part 2-3 m/s, near mountain streams 5-6 m/s.

Physical characteristic.

Temperature is the determining factor.

The change of oceanic and continental influences is expressed in the nature of the thermal regime. Summers are moderately warm and rainy, winters are cold and with little snow. In summer the temperature is from +12 in June to +18-20 in July-August. In winter, from -13 at the end of December to -20 in January.

Ice formations in the form of zabereg and lard usually appear in the second half of October. The river freezes in mid-November, in some areas earlier. Amur opens at the end of the third decade of April. Ice shifts and opening occur at levels that are more or less the same in height; the spring ice drift is relatively calm.

Chemical characterization.

Amur is characterized by a high self-cleaning ability, a positive biological balance and, as a result, a sufficient oxygen content, which ranges from 5 to 6 mg/l.

The pH of the water in the river can change in the annual, seasonal and even daily cycle, but the neutral or slightly alkaline reaction of water prevails (pH 6.5-7.5).

The amount of suspended particles carried by Amur is small, the average turbidity is low, it is 107 g/m 3 . The river basin is located within the turbidity zone from 50 to 150 g/m 3 . The highest turbidity is observed in spring. Due to the high flow rates, the transport of substances is high here.

In chemical terms, the river is characterized by low mineralization, and for the most part belongs to the hydrocarbonate class, sometimes there are waters of hydrocarbonate-sulfate-calcium composition. Mineralization river waters fluctuates both during the year and varies depending on the place of flow through the territory. During the year, Amur carries an average of 18.7 million tons of dissolved substances, which is 54 mg / l. The ionic composition is as follows: Ca - 7.4 mg / l, Mg – 1.6, Cl - 8.0 mg/l.

The concentration in the waters of iron is from 20 to 50 mg/l, manganese - 1.5-11 mg/l, the content of fluorine, copper, cobalt and other trace elements is low. At a number of deposits, water is being purified from iron.

Thus, the water quality of the water supply source of the projected fish hatchery, i.e. r. Cupid meets the biological requirements of herbivorous fish (silver carp and grass carp), as the most preferred temperature for their development is t=18-22 o C. Optimal pH = 7.0-7.5. Herbivorous fish belong to the group of fish that can easily tolerate a decrease in oxygen to 5 mg / l.

CHAPTER 4 Description technological process work of the hatchery

A fish nursery is an enterprise engaged in the cultivation of fish seed: fingerlings and yearlings of semi-anadromous and non-anadromous fish species, including herbivorous ones.

The projected fish hatchery is planned to be built on the banks of the Amur River. It includes pre-spawning, fry, rearing ponds, an incubation shop.

4.1. Harvesting and obtaining mature producers

Herbivorous fish (silver carp and bighead carp, grass carp) are important objects of pond fish farming, they are used to form the ichthyofauna of rivers, lakes, and reservoirs.

The first link in the chain of work on the artificial reproduction of herbivorous fish is the purchase of producers.

Producers are planned to be harvested in May in the tributary of the Amur River - Zeya and brought to the hatchery in slots. Select healthy, intact sires (without wounds, bruises, bruises, cuts) at the age of 6-7 years weighing 5-6 kg and reject old sires.

Producers are treated with a 5% solution of table salt, planted in pre-spawning ponds. The area of ​​pre-spawning ponds is 0.05 - 0.5 ha, the depth is 1.5-2.0 m, they must be quickly filled with water and drained. The stocking density of herbivorous fish spawners in them is up to 1600 pieces/ha. It is necessary to ensure constant water exchange in these ponds in order to prevent excessive heating of the water. Pre-spawning content lasts 30-45 days. This period is important in the life of spawners due to the fact that the last phases of oogenesis end in the pre-spawning period, for which spawners spend a large amount of energy materials. To catch producers, pre-spawning ponds are lowered. Then, fish ready for spawning are selected with the help of cloth sleeves, placed in a stretcher with water, or canvas vats, and transferred to injection ponds.

Individuals are sorted into groups according to the degree of readiness for spawning, exterior, sex. The females are divided into 3 groups. The first group - the best, mature females with a pendulous and soft abdomen, with swelling in the area of ​​​​the genital opening, they are used for work in the first place. The second group - females with similar features, but less pronounced. They are used after finishing work with females of the first group. The third group is females, which appearance do not differ from males, they are not used for caviar production (they are planted for summer feeding).

Males are divided into two groups: 1) easily giving milk; 2) emitting very little milk or non-fluid. They are used at the end of the season or not used for reproduction. Males differ from females in the presence of spines on the pectoral fin from its inner surface. They are the sharpest in silver carp, less sharp in motley, and in grass carp they are very small.

Producers of herbivorous fish are ready to spawn in mid-May - early June.

To accelerate the maturation of sexual products, producers are stimulated by an ecological-physiological method, which consists in providing conditions as close as possible to natural ones (t = 18-22 ° C, pH = 7-7.5, O 2 content = 5-6 mg / l), as well as in the introduction of a physiological preparation of the pituitary gland.

The pituitary gland, or lower cerebral appendage, is an endocrine gland located at the base of the brain. The pituitary gland secretes hormones into the body's circulatory system. The pituitary gonadotropic hormone regulates oogenesis and spermatogenesis, causes the maturation of germ cells, ovulation and sperm formation. The gonadotropic hormone secreted by the pituitary gland enters the bloodstream and stimulates the maturation of germ cells, as well as the release of mature eggs (eggs) from the follicles and the formation of sperm. During spawning, fish producers sweep out mature gametes not all at once, but gradually. So, the female spawns eggs into the water as they ovulate. The movements made by the female lead to the rupture of the following follicles and the continuation of the laying of eggs.

Before starting work on injecting producers, prepared pituitary glands of carp, carp or crucian carp (you can also use a substitute - choreogonic gonadotropin) are ground in a porcelain mortar into powder, then poured with saline (65 mg of salt dissolved in 100 ml of distilled water) and thoroughly mixed. The resulting suspension of the pituitary gland is injected with a syringe into the dorsal muscles of the producers. In this case, the dose of the pituitary gland injected into the fish is determined by the quality of the resulting reproductive products. An insufficient amount of the pituitary gland does not ensure the maturation of the gonads, and an excess one sharply reduces the quality of the resulting reproductive products.

An aqueous suspension of the pituitary gland is injected into the back muscles of the first third of the body (at an acute angle to the body surface) above the lateral line and below the base of the dorsal fin using the Record syringe. The needle is inserted under the scales. After removing the needle, the injection site is clamped with a finger to prevent leakage of the suspension and lightly massaged. This work is carried out in a canvas stretcher with water.

Females with sex glands in the completed fourth stage of maturity are given a preliminary pituitary injection at the rate of 3 mg of dry pituitary gland with a weight of 5--7 kg, and 5-6 mg of the drug - to larger females. A day after the preliminary, a permissive injection of 3-6 mg of the drug per 1 kg of female weight is made, depending on the size of the gonads, and males are also injected. Males weighing 5-7 kg are injected with 4-6, larger ones - up to 10-12 mg of dry matter of the pituitary gland per fish.

Dosages are calculated per 1 kg of fish weight, taking into account the water temperature (Table 1).

Table 1

Required amount pituitary preparation for producers of herbivorous fish

Water temperature during maturation	Dose of the drug per 1 kg of weight, mg	Ripening time, h

The time of injection of producers is chosen, taking into account the temperature of the water and the rate of maturation of the females, so that the receipt and insemination of eggs, laying it in the devices for incubation falls on the daylight hours.

The preliminary injection is carried out, as a rule, at 18-19 pm, allowing - starting from this time and later. However, with sharp cold snaps at night, injections are sometimes carried out in the morning. The rate of maturation of females after a permissive injection strongly depends on the water temperature and is determined as follows: at a temperature of 20-22 ° C, maturation occurs after 10-12 hours, at 23-25 ​​° -9-11, at 26-28 ° C - after 7 -10 o'clock

On the second or third day, males are injected 1 hour before the permissive injection of females.

After 6-9 hours after injection, they begin to regularly check the state of maturity of producers. The interval between these checks is determined depending on the water temperature during the day, the age and condition of the producers, but cannot be more than 1.5-2 hours. This is due to the danger of overripe. For the convenience of manufacturers different sizes, origin, degree of maturity, it is desirable to group. Diverse producers are examined by transplanting them into a free and water-filled cage or container. Determining the exact ripening time is very important. The maturation of reproductive products occurs 10-12 hours after the permissive injection (at a water temperature of 20°C) (Kozlov, 1980).

4.2. Obtaining germ cells, insemination of eggs, preparing eggs for incubation

Sexual products from producers of herbivorous fish (white and mottled silver carp, grass carp) are obtained by straining. Mature females are caught from the cages, carefully wiped with gauze, the head and anal fin are wrapped with a dry napkin. The head of the fish is pressed with the elbow of the left hand to the body, and with this hand the caudal peduncle is held in such a position that the genital opening is above the edge of a clean dish (enamelled or plastic basin), and the abdomen is slightly curved outward. From wall pressure abdominal cavity part of the caviar is released from the genital opening, falling on the edge of the dish, flows down to the bottom. Do not allow eggs to fall directly on the bottom of the dish, as they are easily damaged. After the cessation of free flow of eggs, the abdomen of the female is slightly squeezed and massaged with the fingers of the right hand to the anal fin. With the appearance of lumps of caviar and drops of blood, the straining is stopped.

The amount of caviar is taken into account by the volumetric or weight method. Volumetric method: take three control samples of 50-100 ml, calculate them and find the average number of eggs contained in 1 ml. Then, with a measuring cup or mug, the volume of all collected caviar is measured. The total volume is multiplied by the average number of eggs in 1 ml and the number of collected eggs is obtained in thousand pieces. Weight method: caviar is collected in tared basins, pre-weighed. After straining the eggs, the basin with it is weighed again, and the weight of the eggs is determined by the difference in masses. Three samples of 10 g each are taken from the basin, the number of eggs in each sample is determined and the average number is found in 1 g. Then the mass of the collected caviar is multiplied by the found average value and the total number of eggs in pieces is obtained. The fecundity of females of grass carp and silver carp is from 10 thousand to 2 million eggs.

The preparation of sperm from males is also carried out by straining, massaging the abdomen. Then it is placed in separate test tubes for 30-60 minutes. before receiving caviar, store them in a thermos with ice.

Determination of sperm quality is carried out visually. Good quality semen is creamy, moderately thick and white in color. Determining the quality of sperm is carried out by measuring the volume of ejaculate, the duration of movement of spermatozoa, the ratio of live and dead sperm. Caviar must be intact, have a certain size and color.

Caviar is inseminated in a dry way. Caviar from 3-5 females, moistened with abdominal fluid, is decanted into a clean container. Then sperm from 2-3 males is poured into it, gently stirring with a goose feather. Add a little water, pause for 2-5 minutes. For 1 kg of caviar, 5 ml of sperm are used.

The roe of herbivorous fish is slightly sticky, therefore, before laying it in the incubation apparatus, it is not deglued, it is washed with water from organic matter for 5 minutes.

4.3 Incubation of eggs

Herbivorous fish eggs will be incubated in VNIIPRKh incubators with a capacity of 200 liters (Fig. 8).

Rice. 8. Incubation apparatus "VNIIPRKH"

1-drain pipe; 2-incubation capacity; 3-supply pipe.

The device is a vessel made of organic glass, consisting of an incubation tank, inlet and outlet pipes.

The optimum water temperature during incubation should be 22-25°C, and the oxygen content in the water of the apparatus should be at least 4 mg/l. The survival rate of larvae from eggs is 50%. At the time of caviar loading, the apparatus must be filled with water to 1/3 of the volume, and the water supply to the apparatus must be stopped. Temperature and oxygen conditions are of decisive importance during the incubation of eggs. After loading the caviar, the flow rate is set to 4-8 l/min. Caviar quickly swells in water and after 5-6 minutes its volume doubles. The process of caviar swelling is completed after 2 hours. After that, the optimal flow of water in the incubation apparatus is established. Incubation of eggs at a temperature of 21-25 ºС lasts 23-33 hours.

Care of eggs during incubation is to control its development, to regulate the water supply to the incubation apparatus, the selection of dead eggs. With a siphon, dead caviar should be taken, which in the form of a cloudy white layer is concentrated over live caviar. 3-5 hours before the prelarvae hatch, 100-150 eggs are viewed under a binocular and the percentage of normally developing embryos is determined.

With a high quality of caviar and normal incubation conditions, the yield of free embryos of herbivorous fish is at least 70-80% of the amount of eggs laid for incubation.

4.4 Holding and rearing of prelarvae

4.4.1. Holding of prelarvae. Keeping prelarvae will be carried out in IVL-2 devices (Fig. 9).

Rice. 9. Ventilator-2

1-protective sieve; 2-drain pipe; 3-capacity; 4-water flow divider; 5-supply pipe; 6-hermetic damper.

It is a cylindrical container made of organic glass with a volume of 200 l with water supply and drain pipes, in the lower part of which a water divider is attached, and a protective mesh is installed in the upper part. The water entering the apparatus forms a spiral updraft, simulating the flow of a river. Under these conditions, close to natural, aging takes place practically without waste. The safety net is pulled over metal carcass and tightly installed in the apparatus for the period of exposure.

The duration of keeping the larvae depends on the water temperature and is 90-100 hours at 18-20°C, 80-85 hours at 20-23°C, about 50 hours at 26-27°C. for mixed nutrition, is 50% of the number of fertilized eggs. After resorption of the yolk sac, they feed on the yolk and small crustaceans, which they find in warm water pools. 2-3 hours before being sent for rearing, the larvae are counted by counting 2-3 samples (200-300 ml of a mixture of larvae with water) and further recalculating for the entire volume of the container that is used to keep the larvae.

The final product of the incubation shop is larvae that have switched to mixed nutrition. Larvae at this stage of their development are highly sensitive to changes in external conditions. Therefore, it is currently practiced to rear the larvae of herbivorous fish to more viable stages.

4.4.2. Growing larvae. Growing larvae that have switched to mixed feeding to a weight of 25-30 mg ensures a reduction in the loss of juveniles in the early stages of development and during further cultivation. Factors such as food supply, oxygen regime and water temperature are of paramount importance.

Growing larvae of herbivorous fish is usually carried out in fry ponds with an area of ​​up to 1 ha and an average depth of 1 m. 1500 ind./m 3 . A dust trap made of metal mesh with a mesh of 0.5-1.0 mm (or covered with a nylon sieve No. 32), and on the discharge structure - a fry trap made of a nylon sieve.

After transplanting the larvae into fry ponds, mineral fertilizers are applied at the rate of 50 kg of ammonium nitrate and 20–25 kg of superphosphate per 1 ha. Good results are obtained by introducing into the ponds an aqueous mixture of manure and mineral fertilizers. To do this, 1 ton of manure is mixed with 40 kg of superphosphate and 100 kg of ammonium nitrate, diluted in 10 volumes of water and infused for one day. The shaken mixture is brought in buckets along the water's edge. The abundance of food organisms can be quickly achieved by adding hydrolytic mass prepared from last year's vegetation to the ponds. wooden barrels. The hydrolysis mass is also applied in shallow water. The liquid remaining in the barrels is used for watering sheaves of dried vegetation, laid out along the water's edge of fry ponds.

The need for a certain composition of food organisms in the larvae of all three fish species is different. Thus, the larvae of the silver carp feed on small forms of zooplankton in the early stages of development; later on, they switch to the consumption of larger forms of food organisms, as well as phytoplankton. Larvae of bighead carp and especially grass carp have a wider range of food. So, in their diet at later stages of development, small, large and predatory forms of zooplankton predominate.

Growing is carried out within 14-20 days to a weight of 300-500 mg. Waste for the growing period in fry ponds - 40%.

4.5 Rearing of juveniles.

Growing of juvenile herbivorous fish will be carried out in rearing ponds with an area of ​​30 hectares, with a stocking density of 30-40 thousand pieces/ha. Juveniles are reared in rearing ponds until autumn. Before planting in nursery ponds, larvae are taken into account by the reference method. A certain number of larvae are caught in a special basin (standard). Then, larvae are caught in the same volume of the basin without miscalculation. When the density in 2 basins becomes the same, record the number of larvae. The number of cans is taken into account and, knowing how many larvae are in the standard, they are transferred to the total number.

Nursery ponds should have a well-planned bed and be equipped with water supply trap traps made of mesh with a mesh diameter of not more than 1 mm. Ponds are prepared in advance during operation. After drying, land reclamation work is carried out in them: fish and drainage ditches are cleaned and deepened, hydraulic structures are repaired, dry vegetation is removed, and plowing is carried out in heavily overgrown areas. To create optimal conditions for the development of the natural forage base, 30-40 days before the ponds are flooded, rotted manure is brought into them along the bed. It is evenly distributed with subsequent disking by 5-7 cm.

Juveniles of herbivorous fish are placed in nursery reservoirs no later than 7-10 days after their flooding. Planting of juveniles in gradually flooded ponds with meadow vegetation at the bottom is very effective. Their gradual filling contributes to a better warming of the water and a good development of the food supply for the larvae.

After filling the nursery ponds with water, regular application of mineral fertilizers is necessary. In the process of cultivation, to increase the biomass of phyto - and zooplankton, ammonium nitrate - 60 kg / ha, superphosphate - 50 kg / ha are applied every 2 weeks. In case of a lack of vegetation in nursery ponds, for feeding grass carp on floating wooden frame mowed terrestrial plants are introduced.

It is necessary to regularly monitor the state of the aquatic environment, the growth rate and the physiological state of the fish. Every day at 7, 13 and 19 hours, the water temperature is measured with a mercury water thermometer at a depth of 20-30 cm at the bottom outlet. The content of oxygen dissolved in water during the first growing period is determined every 10 days, from the second half of June - after 5 days, and during periods of a persistent decrease in its content of less than 4 mg/l - daily. At least once a decade, the active reaction of water (pH) is determined. Water transparency is controlled once every three days. Every ten days, control fishing is also carried out in 2-3 characteristic sections of the pond. Since juveniles of herbivorous fish are easily injured, they must be caught with the help of a catcher.

Juveniles of herbivorous fish weighing 20 g are counted and released into natural reservoirs. Departure of juveniles in rearing ponds - 30-50%.

4.6 Accounting and release of juveniles.

Grown juveniles are taken into account before being released into the reservoir by a continuous weight method. All reared juveniles are lowered with the help of Eliseev's devices installed in the span of the lock. This apparatus is a wooden tray, the middle section of the bottom of which is covered with a net. The width of the tray is equal to the width of the gateway span. At the end of the tray there are grooves into which a mesh support with a mesh frame is inserted, which prevents the juveniles from leaving the tray. The water flowing out of the pond goes along the flume and in its bulk is discharged through the section of the mesh bottom, and the juveniles are retained in its small layer. A bucket with mesh walls, suspended on a block, is brought under the stand. Raising the mesh frame, the juveniles are dropped with a small layer of water into this tub. The bucket filled with juveniles is weighed on a dynamometer, and another bucket is brought under the apparatus. The juveniles are then released into the spillway. The mass of juveniles determined on the dynamometer in each tub is recorded in a journal. Every 2 hours, a small control sample is taken and weighed. The sample is disassembled according to size and species composition. Then the number of juveniles is counted individually and the average weight of one specimen is determined. Having established the number of juveniles in the sample taken and knowing total mass juveniles that have rolled down in 2 hours are recalculated by the number of juveniles released during this time.

For transportation of juveniles of herbivorous fish, live fish vehicles will be used at a ratio of fish and water of 1:4. Transport containers for the transport of fish must have sleeves for the rapid descent of water and fish. It is convenient to use polyethylene pipes and other devices for unloading fish. Live-fish machines must have containers in which the required temperature and gas conditions are maintained. When fishing and transporting, it is necessary to exclude injuries.

The release of juveniles will be carried out in the waters of the tributary of the river. Amur - Burei, as this will ensure maximum survival of underyearlings due to the good supply of this river with a food base necessary for herbivores - phyto- and zooplankton. Also in this area there is no bad influence contaminated wastewater.

BIOLOGICAL FEATURES OF HERBIVOROUS FISH

Silver carp (Hypophthalmichthys molitrix Val.). In the pond polyculture of the southern regions of Russia (IV-VI zone), in terms of production volume, silver carp ranks second after carp. Belongs to the carp family. Its homeland is the rivers of Central and South China. Within Russia, it lives in the basin of the river. Cupid. Under natural conditions, it reaches a mass of 30-40 kg. The fish is schooling, occupies the upper and middle horizons of the pond water, more thermophilic than carp, the optimum for growth and intensive feeding is at the level of 25-30 °C. Content in ponds with lower water temperatures, for example, 17-23 ° C, which is typical for the Central and Northern regions Russian Federation, significantly slows down the growth and development of silver carp. With such a temperature regime, at the age of two, it reaches a mass of about 200 g. In the south of the country, the silver carp matures at 3-4 years of age, in the northern regions (I - II fish farming zone) - at 7-8 years. In natural reservoirs, spawning occurs during the flood period in the riverbed on deep rifts with a rocky bottom at a water temperature of 20-25 ° C and above. Fertility - up to 1 million eggs or more, depends on the age and weight of the female. The diameter of the eggs is 1.1-1.3 mm, after fertilization and swelling it reaches 3.5-5.0 mm. Fertilized eggs develop during the drift period in the upper layers

river water.

Embryos hatched from eggs continue to drift until the onset of the larval stage and transition to active feeding. Subsequently, the larvae migrate to the coastal zone and into

shallow bays where they feed and grow. From spawning to the release of embryos from eggs at a water temperature of 24-25 ° C, about 4 days pass. For the first days and weeks, the juveniles feed on zooplankton. After reaching a length of 1.5 cm or more, phytoplankton and detritus become the main food of the silver carp. A favorite food is diatoms and green algae, blue-green algae are consumed worse. In ponds, with intensive feeding of carp with compound feed, it actively strains out small and dusty feed particles that have become inaccessible to carp. The nutrition of the silver carp with phytoplankton is due to the peculiarities of the structure of its gill apparatus, which has a mesh plate with holes of 20-25 microns on the gill arches.

Motleysilver carp(Aristichthys nobilis Rich.). The motley silver carp is a large and strong fish, belongs to the carp family, naturally lives in the rivers of Southeast Asia and in the river. Cupid keeps in the middle layers of water in a dense flock. Schooling persists even in pond conditions.

In the pond polyculture in the conditions of the III zone of fish farming, the bighead carp takes the second place, and in the IV - VI zones in terms of production it takes the third place, it is thermophilic, the highest growth rate is observed at a water temperature of 25-30 ° C. IN temperature conditions in central Russia and to the north, in the presence of a sufficient amount of food, it grows faster than silver carp, two-year-olds reach 300-400 g.

In the conditions of the south, the bighead carp matures at the 6-8th year of life. Fertility is about 500 thousand eggs, in some individuals - up to 1 million eggs or more. Spawning occurs in the same way as in the silver carp, at a water temperature of 20-24 ° C. The nature of nutrition is determined by the structure of the gill filtering apparatus, in which the cells are approximately 2 times larger than those of the silver carp. The distance between the tgchinka

adults is 40-60 microns. The diet of the bighead carp is dominated by zooplankton, whose share in the diet reaches 50% or more, detritus and large forms of phytoplankton. By the nature of nutrition, it is a competitor of carp (especially of the yearlings) in the consumption of zooplankton. This limits the volume of its production in pond polyculture.

Hybrid of white and mottled silver carp. In zones I and II of fish farming, due to the relatively low water temperature and the slow growth of the original species of silver carp, it is recommended to grow their hybrid. The biological features of the hybrid differ little from the original species. The silver carp hybrid has the characteristics of each of the parents. The gill apparatus of the silver carp hybrid acquires the ability to filter out both small and large microalgae and zooplankton. With a lack of zooplankton, the hybrids switch to feeding on phytoplankton and detritus and overtake the bighead carp in growth. In addition, silver carp hybrids have increased vitality.

The hybrids are lighter in color compared to the bighead carp. The keel of the hybrid is longer than that of the variegated one and continues towards the head beyond the pelvic fins. It is more difficult to distinguish a hybrid from a white carp, since they have much in common in color and shape, but the keel of the hybrid is slightly shorter and does not reach the intergill space. In addition, the keel of the hybrid has a less acute angle than that of the silver carp. The hybrid retained the ability to live and feed in the water column, which makes it possible to catch it with conventional screening fishing gear. Eating phytoplankton, zooplankton, detritus and the remains of the pulverized fraction of carp compound feed, the silver carp hybrid, as well as the original species, cleans the pond from excess organic matter, thereby performing the function of a biological reclamator.

Grass carp (Ctenopharyngodon idella Val.). It is a fast growing fish that feeds on higher aquatic vegetation (macrophytes). Under natural conditions, it reaches a mass of 32 kg, but the growth rate largely depends on the water temperature and the presence of vegetation. The optimum temperature for grass carp is in the range of 25-30 °C.

In the Moscow region, white carp mature at the age of 9-10 years, in the south of the country - at 5-6 years. Fertility reaches 700 thousand eggs and more. The spawning biology is the same as that of the silver carp. After fertilization, grass carp eggs quickly swell and have almost the same density as water, which makes them buoyant. The development of caviar occurs during the drift along the river in suspension. Embryos hatched from eggs

continue to develop in flowing water, and after a while they enter quiet backwaters and shallow water, where they feed intensively. Requirements for temperature conditions are similar to silver carp.

When grown in ponds, grass carp completely suppresses the development of higher aquatic vegetation for two to three years, and at the same time actively consumes carp feed, while paying them poorly. Therefore, the standard stocking density of these

fish in pond polyculture is small, and fish productivity is limited to 40-110 kg/ha, depending on the presence and development of macrophytes.

It should be noted that only grass carp and silver carp are fully herbivorous, and then with certain assumptions, since at different periods of life and in different situations they can feed on zooplankton, detritus, mixed fodder, etc.

FEATURES OF BREEDING HERBAL FISH

OBTAINING MATURE SEX PRODUCTS

In the conditions of V - VI zones of fish farming, females of silver carp mature at the age of 3-4 years, bighead carp - 4-5, grass carp - 4 years. Males mature a year earlier. Due to the fact that the fecundity of first maturing females of all three species of herbivorous fish is two times lower than that of re-maturing females, and the eggs and larvae are much smaller than those of older breeders, the use of first-maturing individuals for breeding purposes should be avoided. Females of silver carp should be used at the age of 5 year olds, motley - 5-6 year olds, grass carp - 5 year olds. Males of all three species are transferred to producers a year earlier.

Good results are obtained when using females aged 6-8 years in the 2nd-4th year of operation. Manufacturers older than 10-12 years should not be used.

The fish selected for offspring are sorted by species, sex, groups and, taking into account age, they are planted in ponds for the pre-spawn maintenance of spawners. The area of ​​each such pond is 0.05-0.5 ha, the depth is 1.0-1.5 m. With the establishment of a stable average daily water temperature in these ponds in the range of 19-20 ° C, work begins on obtaining reproductive products from herbivorous fish. The term of the spawning company should not exceed 25-30 days.

To catch spawners, pre-spawning ponds are lowered, the individuals most ready for spawning are selected, and with the help of nets they are placed in a stretcher with water or canvas vats installed on vehicles. Planting density up to 100 kg/m 3 . Fish sorted for reproductive products are kept in spawning cages or containers. Tarpaulin container dimensions 1.55x0.6x0.7 m, water consumption 0.2 l/s, planting density - no more than 2 manufacturers per container.

To stimulate the maturation of reproductive products, acetonated pituitary glands of carp, carp, bream, catfish and choriogonic gonadotropin are used. Hormonal preparations are administered to producers along with an antibiotic (mainly penicillin) to prevent inflammation and death of fish.

Injections are carried out in a stretcher with water. The pituitary substance or choriogonin is administered to manufacturers as an aqueous suspension prepared immediately prior to injection. To prepare the suspension, the pituitary glands are carefully ground in a porcelain mortar. For injection, take a mixture of pituitary glands different weight. The volume of the suspension of the pituitary gland ranges from 1.5-2.5 ml. The injection is made into the muscles of the back above the lateral line, but slightly below the base of the dorsal fin. Hormonal injections stimulate the maturation of oocytes only in the completed IV stage of maturity (subphase E2).

To achieve the effect of maturation of females, fractional injections are used, the first (preliminary) and the second (resolving). Males are injected once. At the beginning of the spawning campaign, the time between injections to females is 24 hours, at the end, when the average daily water temperature is above 24 ° C, the doses of pituitary injections are reduced by 2 times, and the time between them is reduced to 12 hours.

The first dose of pituitary injections for females is 0.5-0.8 mg/kg, the second dose is 4-8 mg/kg. For males - 1.0-1.5 mg / kg. The first dose of choriogonic gonadotropin for females (effective only for silver carps) is 0.2-0.4 thousand IU / kg, the second - 2.0-2.5 thousand IU / kg. For males - 0.75-1.0 thousand IU / kg. The activity of choriogonic gonadotropin is 500:1 (ME: 1 mg pituitary). The antibiotic together with the pituitary suspension is administered intramuscularly with each injection in the amount of 50 thousand IU per fish. The volume of suspension for preliminary injection is 0.5-1.0 ml, for resolving - 1.0-2.0 ml. Males are injected 1 hour before females are injected. The water temperature must be at least 20 °C.

The biological meaning of fractional injections is that the first dose of the hormone causes a displacement of the nucleus in oocytes, which, before the second injection, is closely adjacent to the nuclear membrane. The second dose causes a nuclear transformation, ending with ovulation - the release of eggs from the follicular membranes. The first dose of the hormone promotes pre-ovulation changes in oocytes and turns them into mature eggs, the second promotes ovulation.

After injection, the broodstock are placed in spawning earthen cages or maturation pools at a stocking density of one broodstock per 1 m 3 . Water consumption per 100 kg of fish should be 6 l/s, oxygen content not less than 5 mg/l, water temperature 20-25 °C. The maturation of females after pituitary injections is 80%.

The duration of maturation of females, depending on the temperature of the water after pituitary injections, decreases at a temperature of 20 to 27 ° C from 13 to 6 hours, i.e. with an increase in water temperature by 1 ° C, the maturation time of the female decreases by 1 hour.

With the use of choriogonic gonadotropin, the maturation time of females increases by 1-2 hours. Accurate determination of the maturation time of females is very important, since overexposure of ovulated eggs in the fish body cavity for 30 minutes reduces its quality by 60%, and after an hour, the loss during incubation reaches 96%.

About an hour before maturation of oocytes, the readiness of females is checked. When catching females, spawning cages or pools are lowered, maintaining flow at a low water level. Caviar is obtained in a dark place or under a canopy. The fish is thoroughly wiped with gauze from the water, the eggs from each female are strained separately into dry, clean basins. Mature eggs flow freely from the body cavity of the fish. Quality caviar has little ovarian fluid, its color is from grayish blue to bright orange. Overripe eggs contain a lot of ovarian fluid and some eggs are cloudy white.

During the reproduction of herbivorous fish by the factory method, in contrast to carp, there is a significant post-spawning death of producers, especially silver carp. With a planned normal loss of spawners in the amount of 20%, more than half often die, while in some of the fish that survived, fertility decreases and barren individuals appear. The death of spawners of herbivorous fish occurs mainly for two reasons: traumatization and the use of immature or overripe females.

Traumatization of fish occurs both during fishing and during the injection and straining of eggs and milk. An infection enters the injured areas of the body, as a result, acute inflammatory processes occur, which are especially intense at a water temperature of 25-28 ° C. It is possible that the inflammatory process also arises from the introduction of a foreign pituitary protein into the body of the fish, especially when using fractional injections.

The use of immature females, physiologically unprepared for spawning (having gonads at an incomplete IV stage of maturity) or overripe, in which the processes of resorption of unspawned mature oocytes have gone far, leads to the fact that in such females an insignificant part of oocytes is ovulated upon pituitary injections. As a result, ovulated eggs appear in the gonads, which cannot be swept out by the fish or strained by the fish farmer. These eggs, which have lost contact with the body, undergo rapid decay, which leads to the death of fish. Already after the first injection in such females, clouding of the eyes is observed, often hernial protrusions of a part of the ovary from the genital (genital) opening appear. In order to avoid the use of females that do not mature after pituitary injections and a significant reduction in the death of fish during the spawning campaign, it is necessary to carefully carry out spring evaluation, and work on obtaining offspring - in a short time.

To prevent injury to spawners, it is necessary to use earthen spawning cages with hidden hydraulic structures, to catch fish using canvas sleeves, and to use narcotic drugs. An effective remedy, to a minimum reducing inflammatory processes in manufacturers, is the use of penicillin. The introduction of penicillin does not affect the timing of maturation of females and the quality of offspring.

CAVIAR INCUBATION

Milk is harvested 30-60 minutes before receiving eggs from females. The abdomen of the male is carefully wiped with dry gauze and the milk is strained into dry, clean glass bottles. You can not mix milk from several fish in one container. Storage of sexual products is carried out in wide-mouthed thermoses with ice or in refrigerators. When milk is stored for 10-12 hours, the fertilizing ability of sperm does not decrease.

To determine the quality of sperm, a small amount of milk is applied to a glass slide, a drop of water is placed next to it and they are combined. The movement of sperm cells is observed under a microscope with an eyepiece magnification of 7x, an objective of 8x or 40x with a tightened condenser diaphragm. In high-quality milk, the movement of sperm lasts 15-30 seconds or more. The warmer the water, the shorter the life of the sperm.

Insemination of caviar from each female is carried out in a dry way with pre-prepared milk from 3 males, or milk is immediately expressed for caviar. The milk is carefully distributed over the caviar with a bird's feather and mixed. A little clean water is added to the mixture of caviar with milk and mixed again, at this time the eggs are fertilized. After 1-2 minutes, fresh water is added to the basin with fertilized eggs, mixed and the water is drained. This operation is repeated 1-2 times. With water, lumps of mucus, blood and scales are removed. After washing, the eggs are placed in incubators.

The most common are VNIIPRKh devices for 50, 100 and 200 liters and their modifications - IVL-2 and Amur. The operating characteristics of the devices are given in table 20.

Table 20

The amount of loaded caviar and water consumption

The devices are loaded 5-10 minutes after the fertilization of eggs. Caviar from each female is placed in a separate apparatus, the water in the apparatus is drained to 20-30 liters, the eggs are placed, the water supply is turned on in the operating mode, which ensures the mixing of the eggs throughout the volume. Labels are placed on the apparatus indicating the type of fish, the time and date of receipt of sexual products, the amount of caviar laid.

As the caviar swells and increases in volume, the water exchange is adjusted to a value corresponding to the type of apparatus, the caviar must constantly be in easy movement. After 1.5-2 hours after laying, the percentage of fertilization of eggs at the stage of 4-8 blastomeres is determined. To do this, about 100 eggs are examined under a binocular microscope MBS-1 and the number of normally developing eggs is counted. Benign caviar

fertilized by at least 90%.

3-5 hours before hatching, 100-150 eggs are examined under a microscope and the percentage of abnormally developing embryos is determined. When eggs are incubated with 90% fertilization, 10% deformities and 15% waste of poor-quality fertilized eggs are usually noted, the survival rate for the incubation period is 65%.

During the incubation of eggs (the oxygen regime should be at least 4.0 mg/l), the optimum water exchange regime is maintained, dead eggs are taken with a siphon, which is concentrated in the form of a cloudy white layer over live eggs. The selection of dead eggs is carried out after the completion of gastrulation, at a water temperature of 22-26 ° C, 12-13 hours after fertilization. At the optimal water temperature for incubation equal to 21-25 °C, single embryos first hatch, after 30-60 minutes mass hatching occurs, which lasts for 10 hours. After hatching, free embryos rise to the surface and are carried out of the apparatus by a stream of water. When using the VNIIPRKh apparatus for incubation of eggs, the hatched embryos are sent through hoses to the IVL-2, Amur or Dnepr-1 apparatus, which in such a situation are used for keeping.

When eggs are incubated in these devices, the hatched embryos are kept in them. During aging, mesh inserts are installed in the apparatus and the water supply is turned on. For aging, you can use small cages of nylon sieves. After hatching of the embryos, the walls of the inserts of the devices are filled with shells, which are carefully removed. After a few hours, the remaining shells dissolve in water and are carried into the sewer. After 2-3 days, the walls of cages and inserts are cleaned of silt deposits. By taking daily samples, the estimated time for the transition of larvae to mixed nutrition is determined.

After switching to a mixed diet, they begin to transport the larvae. 2-3 hours before shipment, the number of larvae is counted by counting 2-3 samples (200-300 ml of a mixture of larvae with water) and transferring to the total volume of the storage tank with conversion to the apparatus.

Transportation of larvae is carried out in plastic bags. 10 liters of water are poured into a 40-liter bag, 80 thousand pieces are placed. larvae, fill with oxygen and close with a clamp. Packages for 30 min. left in the shade. During this time, it is determined whether there is a leak from the water and oxygen packages. Next, the packages are placed in cardboard boxes and loaded onto a car. When transporting up to 24 hours, 50 thousand pieces are placed in bags. larvae. The age of the transported larvae is 3-5 days. During the transportation of larvae, sharp fluctuations in temperature, above 30 ° C and below 15 ° C, as well as transportation on a bad road and in unsuitable transport, are unacceptable.