ROSENBERG SHRIMP (Macrobrachium Rosenbergii)

Content

1 Description
2 Behavior
3 Food
4 Contents
5 Shedding
6 Water quality
7 Lighting
8 Diseases

Other names: Macrobrachium rosenberghi, Macrobrachium rosenbergii, Giant Freshwater Prawn, Rosenberg shrimp.
Size: from 13 cm.
Temperature: 26-30 °C.
Water parameters: pH 7.2-8.4.
Behavior: aggressive.
Content difficulty: not for beginners.

Introduction

To date, there are 7 known viral infections to which M. rosenbergii shrimp are susceptible. One of the most serious is white-tail disease, caused by nodavirus (MrNV) and XSV. It significantly increases the mortality rate of M. rosenbergii at the postlarval stage of development. Other pathogens include the Macrobrachium muscle virus (MMV), which causes muscle necrosis, the hepatopancreatic parvovirus, which affects the digestive system, recently discovered in M. rosenbergii - Taihu virus (MrTV), and the Japanese river shrimp reovirus M. nipponense (MnRV).

There are also pathogens that affect other cultivated species but can be transmitted and cause disease outbreaks in freshwater shrimp. These include the IHHNV virus and the WSSV virus, the SHIV virus, the CMNV nodavirus and the EHP virus. In addition, the pathogen Spiroplasma eriocbeiris, which causes spongiform encephalopathy in Chinese mitten crabs (Eriocheir sinensis), was recently discovered in M. rosenbergii. The list of diseases of freshwater shrimp also included the Red Claw Indovirus (Cherax quadricarinatus) - CQIV, which is characteristic of crayfish. Below is more information about some shrimp diseases.

Viral diseases of the giant freshwater shrimp (Macrobrachium rosenbergii)

Description

Over the past 15 years, giant Rosenberg shrimp have become an object of desire for many aquarists. They grow quickly, reaching a body size of 13 cm at 10 months or even earlier. These shrimp are perfectly protected, like an armored knight, almost the entire body is protected. But, unlike the knight, shrimp show excellent coordination and dexterity. The color of the shrimp may be darker or lighter depending on the color of the soil. Juveniles are almost transparent. Growing individuals are less transparent and may be covered with blue stripes.

In nature, adult females are dark brown with black claws and orange antennae. Adult males are dark blue or brown. In fact, the shell contains a large number of pigments, including black, neon blue, and yellow or orange carotenoids. Some colors may appear and disappear.

Where to get shrimp for breeding

In Russia there is only one farm for growing Pacific shrimp, but there may be private aqua farms. You need to choose them carefully, having studied all the nuances of their activities. It is important to buy high-quality planting material, otherwise the process will not complete successfully and the crustaceans will die.

Large shrimp farms, where crustaceans are grown for sale around the world, are located in Southeast Asia. The main problem is that shipping live specimens to Russia will be very expensive, and there is no guarantee that the material will remain viable.

Behavior

In the aquarium, these shrimp seem to spend most of their time cleaning. Six long tentacles are covered with receptors that allow them to detect the smell of food in water. They constantly clean themselves, removing pieces of dirt that may affect their sensitivity. They clean everything from claws to eyes.

They are highly social animals, especially during courtship. The male grabs, lifts, pinches and even hugs the female with his claws. In general, these animals are almost constantly doing something, you can watch them almost endlessly.

Compatibility

A group of shrimp consists of a dominant male and subordinate individuals. The first constantly defends leadership and territorial claims, engaging in brutal fights with other males. Weak opponents who did not have time to retreat to cover are often left without claws.

Compatibility with other crustaceans is difficult to predict. It is undesirable to introduce small crustaceans and mollusks, even those protected by a shell: the macrobrachium will perceive them as food. Although, if the shrimp is full, it may not pay attention to its small neighbors.

Macrobrachium is clumsy and is unlikely to be able to catch nimble fish, although it will certainly try. But at night it is capable of sneakily attacking a dozing fish. Also eats caviar. Therefore, it is preferable for macrobrachium shrimp to be kept in a separate tank. In a common aquarium, neighbors should be active fish swimming in the upper half of the water column:

Mollies;
Barbs;
Danio;
Rainbows.

Nutrition

The Rosenberg shrimp eats everything. In the wild, they eat pieces of worms, snails, shellfish, fish, pieces of rice, wheat, beans, nuts, aquatic plants and some fruits. According to the experience of many owners of these shrimp, the most favorite dishes are shrimp pellets, pieces of squid and fish, live tubifex worms, and some algae. Another great nutritional addition would be egg cream. Shrimp also eat flake fish food. However, cereal alone will not be enough to provide adequate nutrition. Like fish, shrimp do not always start eating live food right away. But be patient and they will eventually eat everything.

Rosenberg shrimp are not picky and are not difficult to keep. Adult shrimp, especially females, are very voracious and are capable of catching even nimble small fish.

Plants will also not be left unattended; most of them will simply be uprooted and eaten. Even plastic plants can become damaged from time to time.

However, some aquarists have found a way out. They place very small specimens in a stocked aquarium with greenery, for example, with tetras and guppies, and these very problematic shrimp raised in such an environment behaved well and no fights occurred. I think experienced aquarists might have noticed that the care and maintenance of these shrimp is not much different from, for example, cichlids.

Features of feeding

The Rosenberg shrimp is an omnivore, so there are usually no problems feeding it at home. Crustaceans happily consume both natural and frozen or dry food. It is recommended to periodically feed mollusks with tubifex, daphnia, etc. After all, as predators, giant shrimp need live, high-protein food.

Rosenberg shrimp will certainly enjoy chopped fruits and vegetables, herbs pre-processed in boiling water, as well as leaf blades of various plants.

To maintain an optimally balanced diet, a combination of animal and plant foods is recommended, but a large percentage of the menu should consist of live food.

In addition, in pet stores you can purchase ready-made food intended specifically for feeding crustaceans. It is recommended to feed the shrimp once every 1-2 days, trying to calculate the amount of food so that it is immediately eaten and does not have time to settle to the bottom, since otherwise you will have to clean the soil and siphon the soil (read more about how to properly siphon the soil in an aquarium) .

Content

Rosenberg shrimp need territory. Juveniles may share a territory with other individuals, but once they reach 5 cm, their claws become strong enough for them to defend their territory. At this age, the shrimp should have at least 600 cm² of bottom area, or about 120 cm² for every centimeter of body length. Adults 12 cm or more in length must live in a volume of at least 75 liters. In one aquarium you can keep a pair or 1 male and 2 females.

Overcrowding, poor water quality, or poor nutrition can all lead to aggressive behavior, leading to injury or death, especially during molting.

How much money do you need to start a business?

Let's look at capital investments using the example of creating a shrimp farm. For the startup we will need:

Industrial premises with utilities (water, sewerage, electricity). Area 120 – 150 sq. m. Annual rent 180,000 rubles.
Utility bills – 150,000 rubles.
Equipment (swimming pools, RAS, generator) - 500,000 rubles. You can take smaller and cheaper units, or used ones, but we look at the average price tag for the country.
Purchase of shrimp stock (1,000 individuals) or fry for breeding – 30,000 rubles.
The annual supply of feed is 120,000 rubles.
Hired workers - 300,000 rubles. Someone must monitor the condition of the pools, water indicators, and temperature.
That is, to create a more or less liquid farm at the initial stage, we will need about 1,300,000 rubles. With such investments it is possible to produce up to 5 tons of seafood per year. From the second year, we exclude expenses for equipment and young animals, and we get about 750,000 rubles in annual investments.

Shedding

Molting is the process that allows shrimp to grow. Although their thick shells provide excellent protection, it limits growth. Once in a while, shrimp must change their shells. Young shrimp molt much more often, once every two to three days. But as they get older, their growth slows down.

Adult females molt every 20-40 days, while males may molt once every six months. The molting process is very interesting. Before molting, shrimp grow a new shell under the old one. But this new shell is very soft and a little wrinkled. At this time, the shrimp begin to absorb some of the calcium from the shell, weakening its parts.

You can tell when a shrimp is about to molt by the loss of appetite, especially in adults. When molting, the new shell swells with water, splitting the old one in weakened areas. The old shell is bursting. A sharp movement of the tail frees the shrimp from the old shell, leaving it lying on the bottom of the aquarium.

The shrimp will continue to fill with water, which will later be replaced by new tissue. For a short time, about 15 minutes, the shrimp will be unable to walk or use its claws. The flexible new shell does not yet provide enough support for muscle action. After half an hour, the cover will become hard enough and the shrimp will be able to move normally.

The shell will completely harden only after a few days. All this time the shrimp are very vulnerable. For this reason, it is necessary to provide places where shrimp can hide to avoid stress, which will have a positive effect on their well-being. Although, of course, the main prevention against cannibalism remains good water quality and good nutrition.

Rosenberg shrimp, an intensive method of cultivation and reproduction.

Giant freshwater shrimp Macrobrachium rosenbergii In fresh waters, mainly representatives of two families are found: Palaemonidae and Atyidae. Only one genus, Macrobrachium, is of commercial importance, species of which reach quite significant sizes - from 50 to more than 300 mm. Freshwater shrimp of the genus Macrobrachium are widespread in tropical and subtropical regions of the world. Beyond its native range, the giant freshwater shrimp is acclimatized and successfully cultured. All populations of M. rosenbergiі are divided into western and eastern groups, which differ in a number of characteristics: resistance of juveniles to salinity and high temperature; growth rate; features of larval development. The eastern group includes the Australian and northeastern parts. Shrimp populations of the first of these are characterized by short larval development. The shrimp of the Philippine population are significantly different from others. However, despite the differences, shrimp of all populations of M. rosenbergii freely interbreed with each other, producing viable offspring. Intraspecific hybridization is also possible, which gives great scope for breeding crossed forms with given properties. The main habitats of the giant freshwater shrimp (as well as most species of the genus Macrobrachium) are lower reaches of rivers and estuaries. Adults usually live at the bottom of rivers, migrating to spawn in brackish and salt water (10-30% o) near the mouth. The larval period takes place in estuaries. The larvae are the most stenobiont, the biontity of juveniles is somewhat wider, and the adults are eurybiont. Optimal conditions are basically the same for all stages: water temperature - 28-30 C, illumination - about 4000 lux, water saturation with oxygen - about 70%, pH - 7-8, nitrite content - no more than 0.1 mg/l , nitrates - no more than 20 mg/l, water hardness (CaCO.) 30 - A high concentration of calcium promotes better development of larvae and adult shrimp. The lifespan of the giant freshwater shrimp is 3-4 years. Reproduction of the giant freshwater shrimp The life cycle of M. rosenbergii consists of the following periods: embryonic, larval, juvenile and adult (Fig. 1) Freshwater shrimp are dioecious. In the female, the reproductive system consists of paired ovaries, oviducts and gonopores. The ovary lies dorsal to the stomach and hepatopancreas. In a mature female, the ovaries are orange in color and are clearly visible through the carapace. The process of egg maturation and the growth of the gonad can be divided into 2 phases: the formation of eggs, which gradually fill the ovary, and the accumulation of yolk by the eggs. The male reproductive system consists of paired testes, seminal ducts and gonopores. The testes are small and occupy a position similar to the anterior lobe of the ovary in females. In a giant freshwater shrimp

Diagram of the life cycle of a giant freshwater shrimp, adult males are usually much larger than females (about 1.5 times). Males have a wide cephalothorax and more powerful claws, while females have a relatively larger abdomen. The genital openings in males are located between the bases of the fifth pair of pleopods, and in females - at the base of the third. The pleura of females is longer, and in combination with a wider abdomen forms a large brood chamber. In the natural conditions of the tropics, shrimp of the genus Macrobrachium mate sporadically all year round. The intensity of reproduction increases during the seasonal rains (monsoon period). At this time, the likelihood of larvae entering estuaries with water runoff increases, where there are optimal conditions for their development and growth. In acclimatization areas, temperature becomes the main limiting factor. It should exceed 22 C. Shrimp reach maturity at the age of 4-5 months. Females mature earlier than males with a length of about 80 mm and a weight of about 6.8-8 g. The length and weight of males that begin to mature are about 100 mm and 10. Mating and spawning behavior in different species of the genus Macrobrachium have been described in many works since “soft” females who have finished molting. In this case, the male is next to the female at the time of molting, protecting her from other shrimp and predators. During mating, the male deposits a gelatinous spermatophore near the opening of the female's gonopores. External fertilization occurs 5-10 hours after mating, when eggs emerge from the female’s gonopores through the oviducts. They are fertilized by sperm located in the spermatophore. Unfertilized eggs die after 2-3 days. and is dropped by the female from the pleopods. The fertilized eggs are transferred to the brood chamber and held there by the abdominal pleura. The female ensures continuous washing of the eggs with fresh water by movement of the pleopods. The fertility of females depends on their size and increases with age from 20 to 150 thousand eggs or more. The fertility of females 118 mm long is 21,270 eggs. Females 120-130 mm long have a fertility of 20-30 thousand eggs. Larger females have larger eggs. At the same time, the survival rate of embryos from large females is higher than from medium and small ones. After reaching sexual maturity, the growth of females slows down, while the growth of males continues at the same pace. By the age of 7 months, individual individuals reach 100-120 g, by the year - 140-150 g, sometimes up to 200 g. The average number of eggs per 1 g of body weight varies depending on the size of the females from 870 to 1100 pieces). Early ontogenesis of the giant freshwater shrimp. Embryonic and larval periods.

The rate of embryogenesis is largely determined by water temperature and for freshwater shrimp it is 11–30 days. in the temperature range of 21-33 C. The optimal temperature is 27-29 C. During embryogenesis, the eggs change color from orange to yellow and then gray. Hatching of the larvae occurs within 1-3 days. The larval period takes place in estuaries. The larvae can remain in fresh water for no more than five days. The optimal water salinity for larvae is 12-14%o, for juvenile adult shrimp - 0-8%o, although the latter are tolerant to this factor and can develop successfully at a salinity of 0-30%o. For larvae, water temperatures below 18 C and above 34 C are lethal; for adults - below 13 C above 37 C, although feeding and growth cease already at temperatures below 18 C. The last larval moult occurs with metamorphosis. The resulting postlarvae lead a bottom lifestyle. In the natural environment, larval mortality reaches 99%. The main causes of mortality: poor water quality, sharp fluctuations in salinity, diseases, planktivorous predators, lack of food, etc.

Postlarval (juvenile) period

. During this period, shrimp have a size of 7 to 10 mm and a weight of 6 to 9 mg. In their structure and lifestyle, postlarvae differ little from adult individuals. They have a high tolerance to water temperature and salinity. The morphological structure of postlarvae is adapted to the benthic lifestyle. Despite this, in the first days after metamorphosis, especially at night, they lead a pelagic lifestyle. After the transition to a bottom lifestyle, postlarvae feed on small benthos, detritus, plant and animal remains. On average, under optimal environmental conditions, postlarvae reach a mass of 0.5 g and a length of 50-60 mm within 2 months. Postlarvae, unlike larvae, swim due to the forward movement of the pleopods with the rostrum, the dorsal part of the body is at the top. They can make rapid movements, sharply contracting the abdominal muscles. In their natural environment, they begin to migrate upstream. Juveniles swim against fast-flowing streams or crawl along rocky bottoms. The giant freshwater shrimp never buries itself in the sand or digs holes, but hides in shelters or in the shadows of objects. It feeds and is active mainly at twilight and at night, and is inactive during the day. Eating behavior can be divided into three stages: increased search activity, movement to a food source; contact and testing of food. Shrimp are polyphagous, capable of feeding on both living and non-living food. Thus, in the delta of the Purari River (New Guinea), the giant freshwater shrimp feeds on crustaceans, mollusks, and higher aquatic vegetation; in the rice fields of India, rice grains, sand, and detritus were found in her stomach; in the reservoirs of Thailand, its diet consists of insect larvae, small crustaceans, plant and animal detritus. The growth of shrimp, like other representatives of Decapoda, occurs in steps, after molting, when changing the shell. The molting process takes several minutes: the old shell bursts between the chest and abdomen, the shrimp bends sharply, and with its two front pereopods pulls the shell off the cephalothorax and frees the abdomen. The shed exuvium is partially or completely eaten to replenish calcium and other necessary substances. After molting, until the integument hardens, the shrimp does not feed for some time and remains in the shelter. Molting is a critical moment in the life cycle of shrimp: it is at this point that maximum mortality occurs. When molting, one or both claws are often lost, which aggravates the defenselessness of the molted individual. The intervals between molts vary depending on the age of the individual, nutrition, temperature, water hardness, etc. For example, at a water temperature of 27-28 C, juvenile shrimp 4-6 cm long molt after 6-11 days, 7-9 cm long - after 13-15 days, adult shrimp - after 26-93 days. The frequency of molting increases under the influence of hormones released into the water by molted shrimp, which causes partial synchronization of molting. Adult females usually molt at least 10 times a year, with 4-5 and sometimes 7 molts being reproductive. Thus, the most vulnerable stages in the ontogeny of the giant freshwater shrimp are the larval stages. During the larval period, the shrimp is most stenobiontic, and its mortality rate is highest. Using aquaculture methods, by creating optimal development conditions, it is possible to increase the realization of the bioproduction potential of the species.

Broodstock, embryonic period of the giant freshwater shrimp. Formation and maintenance of broodstock. The formation of the broodstock is carried out from reared sexually mature individuals with intact pereopods, typical pigmentation of the carapace and, in males, claws (which are blue). The weight of females is usually 15–30 T (85–150 mm), males 40–80 g (165–225 mm). In the broodstock, the optimal ratio of males and females is maintained - 1:4 Female M. rosenbergi immediately after fertilization. During incubation, the optimal light mode is maintained - 12:12 (light: dark), illumination - 500–1000. Embryonic period of the giant freshwater shrimp At a water temperature of 26-28 C under controlled conditions of a closed water supply cycle, the embryonic period of development is 18-20 days (486-540 degree days). The eggs acquire a gray tint 15-17 days after fertilization. At this moment (2-3 days before the start of hatching), the females are placed in containers for pre-incubation and hatching of the larvae.

Water salinity is 12-14%. Brackish water is the natural habitat of larvae in natural conditions and also has a disinfecting effect on embryos and larvae when reared in artificial conditions. In our practice, survival rate is 60-65%. Immediately before hatching, the female bends her cephalothorax low, with a sharp movement of the pleopods she raises a wave of water and, thereby, causes a water shock to the eggs. This promotes the activation of embryo movement, rupture of the egg membrane and hatching of the larvae, which lasts 1-2 days. After hatching the larvae, we place the females from the nursery tanks back to the males. 2-3 days after hatching, the females molt. Some females laid eggs of the next generation immediately after molting, while others had two or more molts in the interval between clutches. Under our cultivation conditions, the shrimp laid a new batch of eggs 10–35 days after the larvae of the previous clutch hatched.

Like the larvae of many decapods, zoea shrimp lead a planktonic lifestyle and are always in the water column. Only during molting do the larvae sink to the bottom. They move by sudden vertical movements, head down. This orientation during movement is primarily due to the massiveness of the head compared to the rest of the larval body. Development and growth of giant freshwater shrimp The average duration of development of planktonic larvae to postlarvae, according to our data, is 30-36 days. In this case, the first postlarvae hatch on the 26th-27th day from the moment of hatching. According to the observations of other authors, the duration of larval development in M. rosenbergii can be longer - from 35 to 50 days; according to some data, when larvae of this species are reared in artificial sea water, the duration of the period was 29-55 days. Consequently, temperature control of water at a level of 28-31 C, in the closed-cycle installations we used, made it possible to reduce the duration of the larval period by a maximum of 29 days. At the first stage of development, the body length averages 2.3+0.014 mm, with 0.025+0.009 mg wet weight. The dependence of the larval body length on the rearing time is well approximated by the formula: L=0.188T+1.54, where L is body length, mm; T is the number of days after hatching (correlation coefficient - 0.98). Consequently, we obtained not only a reduction in the larval period of development of the giant freshwater shrimp, but also a simultaneous acceleration of growth. Each stage of development takes place in 1-4 days. However, the molts of individual individuals are not synchronous. The greatest asynchrony of molts is observed on days 27–36, when the metamorphosis of the first larvae into postlarvae occurs. Thus, the first postlarvae appeared on the 27th day after hatching. On the 34th day, the proportion of postlarvae was 68% of all individuals, and only on the 36th day - 80%. Asynchrony of molts causes increased cannibalism, which is the main cause of mortality. During the “larval period”, survival rate under controlled conditions of a closed water supply cycle at a stocking density of 100 pcs/l averaged 52%, varying in different containers from 40 to 60%. According to literature data, the survival rate of M. rosenbergii larvae in a recirculation system at a salinity of 12% o and a temperature of 28 C is 30-60%. When the planting density is reduced to 30-50 pcs/l, the survival rate of larvae increases to 50-70%, the larval period is 34-36 days and the planting density is 70 pcs/l. Our results are close to those given above and indicate that in conditions of a closed water supply cycle it is possible to rear giant freshwater shrimp larvae at high stocking densities with good survival. A further increase in survival rate while maintaining a high stocking density is possible by synchronizing the larval moults under artificial conditions. A decrease in the survival rate of shrimp larvae in natural and artificial growing conditions also occurs due to diseases that arise when the quality of the growing environment deteriorates, the development of epibionts (bacteria, algae, protozoa), and non-compliance with biotechnological growing standards. In our experiments, when growing larvae in controlled conditions of installations with a closed water supply cycle on artificial sea water, the incidence of shrimp diseases was practically absent. Food and feeding of the giant freshwater larva The larvae of the giant freshwater shrimp are not capable of actively pursuing victims and can only capture objects that come into contact with them. In this regard, the most acceptable food is crustacean nauplii and other zooplankton. Larvae can consume suspended detritus particles. Larvae of the 1st stage feed endogenously; at subsequent stages they switch to exogenous nutrition. According to our own data, the larvae begin to feed on the second day after. To optimize the technology for cultivating giant freshwater shrimp in a closed water supply system, we developed and tested an original method of feeding larvae. The essence of the method is that larvae and postlarvae were fed with Artemia nauplii at the age of 12-24 hours and an egg mixture prepared from boiled eggs and milk powder in a ratio of 1:2. The composition and size of food particles, as well as the feeding regime, were varied depending on the developmental stage of the shrimp.

In the previously developed methods for cultivating juvenile shrimp, the optimization of the temperature and hydrochemical parameters of the aquatic environment was mainly carried out, and attempts were also made to jointly cultivate shrimp, zooplankton, phytoplankton and fish. For example, in the work of D. Stepanov and co-authors, when co-cultivating giant freshwater shrimp larvae with zooplankton, phytoplankton and aquarium fish, under conditions of a closed water supply cycle, the concentration of zooplankton was set to be insufficient for adequate nutrition of the larvae - 5 pcs./L. The survival rate of larvae is not indicated in the work, which does not allow us to evaluate the effectiveness of the proposed rearing method. In some commercial farms, clean and so-called “green” water is used for growing larvae - with a high content of phytoplankton (about 1 million cells per liter). To develop phytoplankton (mainly chlorella), fertilizers are added to the water: superphosphate, urea, urea and complex (nitrogen, phosphorus, potassium) mineral fertilizers. Shrimp larvae cannot digest phytoplankton even if they ingest it. But algae can serve as food for artemia nauplii, which, in turn, feed on shrimp larvae. The use of “green” water in cultivation increases the yield of postlarvae by 10-20%. However, with this method it is difficult to maintain environmental parameters at an optimal level. In particular, the pH can increase to 10-10.5 (for larvae the lethal pH value is 9.5). Therefore, a number of farms have been switched to mixed water supply systems (a mixture of fresh and “green” water). With our method, the density of postlarvae in a closed water supply system is 52 pcs./L. Thus, the new method we developed can be used in the industrial cultivation of giant freshwater shrimp. The feasibility of using the method in practice is proven by higher rates of survival, growth of shrimp, and stocking density while simultaneously reducing the duration of development than when using known methods.

Growing postlarvae to market size. General characteristics of development and growth The body length of newly molted postlarvae was 8.34+0.05 mm, weight - 7.81+0.94 mg. To prevent cannibalism, on the 34th day after hatching, postlarvae were transferred to separate containers, in which water was desalinated for 10–12 hours. When dividing, differences in behavior were used - larvae swim in the water column, postlarvae lead a bottom lifestyle. Postlarvae were reared for 30–45 days with a gradual decrease in planting density. In the first week of cultivation, the planting density of postlarvae was 5000 pcs./m2. To reduce cannibalism, in the second week the planting density was reduced to 2000 pcs./m2. In the third week, re-sorting was carried out with a decrease in planting density to 1000 pcs/m2. During the first week, postlarvae were fed Artemia nauplii and egg mixture 5 times a day. From the second week until the end of the postlarval period, minced fish was included in the diet. Older postlarvae were fed 4 times a day. The daily diet at the beginning of development was 100% of body weight. Then, by the 45th day of development, it was gradually reduced to 15%. Survival rate was 70%, weight at the end of the postlarval period varied from 0.08 to 0.20 g, length 18–25 mm. Stocking density is the dominant factor affecting the growth and survival of giant freshwater shrimp in aquaculture, regardless of rearing methods. The influence of temperature on the development of juvenile giant freshwater shrimp (pilot experiment of the Coral Fish company) When growing shrimp, it is recommended to use a temperature of 26-30 C. Temperature tolerance range is 15-37 C. The purpose of our experiment was to determine a narrower temperature range at which growth rate and survival are best combined. The maximum average daily increase was noted at a growing temperature of 30.1 to 32.0 C. Survival at this temperature was also close to the maximum - 85.2%. As a result, the maximum final biomass is obtained. At a temperature of 28.1–30.0 C, due to good survival and average growth rates, the final biomass was 94.0 g and was the second largest. The best survival rate (90.4%) was observed at low temperatures for rearing juveniles (from 26.1 to 28.0 C). The reduction in mortality at low temperatures occurred due to a decrease in the frequency of molting and, accordingly, a weakening of cannibalism. At the same time, the daily increase under these temperature conditions was minimal - 1.8 mg, which led to a decrease in the final biomass to 60.8 g. At elevated water temperatures (32.1-34.0 C), the frequency of molting increased, which increased mortality from cannibalism. Motor activity also increased. As a result of the additional energy required for movement, growth rates were worse than in the previous temperature range. Thus, for growing juvenile giant freshwater shrimp, a temperature range of 30.1–32.0 C can be recommended as optimal. A water temperature of 28.1–30.0 C can be considered acceptable for effective cultivation. A decrease or increase in water temperature relative to the above ranges leads to a deterioration in cultivation performance. The influence of the initial size of juveniles on growth and maturation. Asynchrony of molts leads to significant differences in individual growth rates. Thus, after 107 days of cultivation from the moment of hatching (75 days after metamorphosis of the larvae), at a stocking density of 500 pcs./m2, we obtained juveniles with a length of 4.19 to 6.16 cm.

The largest shrimp retained their advantage in size, reaching a weight of 20.12 g and a length of 11.39 cm in 125 days. Small specimens, when reared separately from large ones, did not surpass the latter in size. The giant freshwater shrimp is characterized by sexual differences in growth: females grow evenly, males are divided into groups according to the predominance of somatic or generative growth. Small males with uncolored claws and males with blue claws actively participate in reproduction, while their growth rate is low. Large males with orange claws grow rapidly. At the age of 200 days after hatching, they are all sexually mature, but do not participate in reproduction. It is possible for males to transition from one morphological type to another. Separation of cultured shrimp by morphotype can improve the efficiency of biotechnology. Thus, when a monosexual culture is formed from individuals with orange claws, the production of commercial products increases due to accelerated growth. Males with blue claws are selected for breeding. In giant freshwater shrimp at the age of 200 days from the moment of hatching, we studied the ratio of male morphotypes and the ratio of females at various stages of the generative cycle in different size groups.

Clarification of the patterns of formation of morphological types of male freshwater shrimp is important for industrial cultivation and should be continued in the future. The influence of stocking density and shelter area on the development of juveniles The main methods for reducing cannibalism are reducing stocking density and increasing the shelter area. The effectiveness of these techniques and their parallel use was assessed in our experiments. With early juvenile shrimp at the age of 80 days from the moment of hatching (45 days after metamorphosis of the larvae), five variants of the experiment were carried out, differing in the combination of the specific area of shelters and the density of shrimp planting. At low planting densities (140 and 170 pcs./m3), increasing the specific area of shelters by 2 times (from 19.4 to 38.8 m2/m3) leads to only a slight increase in survival rate: from 68.6 to 73.5%. However, with a larger shelter area, despite a simultaneous slight increase in planting density (up to 170 pcs./m3), the average daily gains exceed those with a low planting density (140 pcs./m3): 0.053 and 0.048 g, respectively. At a high planting density (750 pcs/m3), an increase in the specific area of shelters from 38.8 to 48.5 m2/m3 practically does not increase the survival rate of 60.1%. Consequently, in the presence of shelters, the optimal density for cultivation of early juvenile shrimp is 600-750 pcs./m3 or 250-312.5 pcs./m2 of the bottom. The use of shelters when growing shrimp allows you to simultaneously reduce cannibalism and increase the specific surface area, thereby using not only the bottom of the container, but also the entire volume. The biotechnology of cultivating giant freshwater shrimp in installations with a closed type of water supply makes it possible to more fully realize the bioproductive capabilities of the species by increasing the survival rate of larvae, compared to natural conditions, by 45–60 times, and reducing the larval development period by 1.8–2.0 times. , increasing the stocking density of juveniles during commercial rearing by 5.0–11.0 times, while maintaining the growth rate at the level of the best achievements,

Commercial cultivation in closed circulation plants The stocking density of juvenile shrimp (at the age of 35-100 days from hatching) for commercial cultivation can range from 45 to 75 pcs./m2. The greatest difficulties in growing shrimp at high stocking densities are caused by cannibalism, especially in intensive farms. In order to reduce cannibalism, we have developed a closed circulation plant for the industrial year-round cultivation of giant freshwater shrimp. The technical objective of the installation was to reduce the occupied area of equipment (the tanks are integrated into tiers), reduce energy costs for equipment of the RAS system, increase the efficiency of using a modular installation when growing crustaceans in a closed water replacement cycle (providing shelters (substrate, to reduce cannibalism), which simultaneously provides the possibility of self-preservation of molting shrimp individuals and the biological film developing on the substrate is actively used by shrimp as food, which increases their growth rate. Technological system of a modular type RAS (description and technical characteristics can be seen on our website (https://coralfish.ru/uzv -dlya-krevetki-rozenberga-macrobrachium-rosenbergii) When grown in the installation we designed, shrimp at the age of 100 days from hatching reach the minimum marketable weight (30 g) when fed with specialized food developed by our company. Stocking density up to 75 pcs/m2, survival rate - 89%. Thus, the installation we have developed is currently the most effective for the commercial cultivation of giant freshwater shrimp.

Commercial cultivation in open reservoirs Let us consider the generalized experience of commercial cultivation of giant freshwater shrimp in open reservoirs

1. The broodstock is kept indoors from October to May;

2. From mid-January to May, larvae are obtained and raised in a closed system with sea water;

3. From May to October, intensive pond or cage cultivation is carried out to market size.

Already grown juveniles are usually placed in ponds at a stocking density of 20-50 thousand individuals/ha. Fishing is carried out once at the end of the season; the growing season in open water bodies can last from 3 to 5 months. When using planting material weighing 0.3-3 g, during this time you can get commercial size shrimp (over 100 g). Due to uneven growth, some of the individuals, the number of which depends on the duration of cultivation and planting density, do not reach marketable size.

There are several ways to increase the number of large-sized shrimp towards the end of the growing season in open waters;

— rearing of juveniles in controlled conditions before planting in ponds; — reduction of planting density; at the same time, however, the total yield decreases; — introducing shelters into the reservoir, increasing the useful growing area; — selective catching in the process of growing the largest individuals, as a result of which the growth rate of the remaining ones increases.

You can increase productivity by growing same-sex shrimp. The productivity of a group consisting of only males is superior to the productivity of mixed groups or groups of females

Note: cultivation duration is 120 days; pond area - 0.4 hectares; planting density - 12.5 thousand specimens/ha. Shrimp lead a predominantly bottom-dwelling lifestyle, so when cultivated in a monoculture, the water column remains unused, which makes it advisable to grow them together with fish. The following hydrobionts are suitable for cultivation with shrimp and have been tested in practice: carp, tilapia, channel catfish, grass carp, silver carp and freshwater crayfish. To increase the natural productivity of reservoirs, they are fertilized with mineral and organic fertilizers. Yields from giant freshwater shrimp farming vary depending on climate, degree of intensification of production, feed used and much more.

Feed and feeding.

Shrimp are polyphagous. In extensive farms, when they are grown open to commercial size, various feeds of local origin are used, for example: grain seeds, algae, small shellfish, cyclops, fish eggs and fish processing waste, fresh and pressed leaves, cow spleen, orange pulp and frozen bananas, carrots and many others, once a day.. The protein content in the feed should be 24-38% (lipids from 6 to 9%). Since specialized shrimp feed is not produced in Russia, the following are used for various cultivation options feed: minced fish mixed with squid, carp feed, fish and poultry waste, aquatic vegetation, etc.

For feeding, you can use trout (salmon) granulated food with a protein content of up to 40%. Biotechnical standards Shrimp farming with a closed water supply cycle consists of the following blocks.

1. Block for keeping broodstock.

2. Block for growing larvae.

3. Block for growing planting material.

4. Block for commercial cultivation.

The first, third and fourth blocks work with fresh water, the second - with brackish water. Each block has several independently operating modules, including aeration, thermoregulation and water purification systems (mechanical and biological filters). A particularly high degree of purification is required when growing larvae. At all stages of development, the following environmental parameters are maintained: dissolved oxygen content - no less than 5 mg/l, pH - 7.0-8.0, nitrite content - no more than 0.1 MT/II, nitrates - no more than 20 mg/l .

Maintenance of broodstock.

Producers are kept at a stocking density of no more than 5 pcs/m2, with a ratio of 1 male to 3–4 females. To prevent cannibalism, vertical and horizontal substrates (shelters) are placed in containers. The optimal water depth in trays is 30-45 cm. Feed for producers must contain at least 30% protein. After fertilization of the eggs, the females are placed in a separate container. The progress of embryogenesis is monitored by changes in the color of the eggs. Two to three days before hatching, the female is transferred to the incubator. After hatching the larvae, the female is returned to the broodstock. The larvae are reared at a water temperature of 28-31 C and salinity of 12-14%. Sea water is obtained from artificial sea salt for aquariums (from Sera, Germany. Feeding begins 2 days after hatching according to a differentiated scheme, depending on age. After metamorphosis of 100% of the larvae, water is desalinated within 4–5 hours.

Rearing postlarvae (juveniles).

For the cultivation of postlarvae, a particularly important condition is the presence of a substrate (shelter). The planting density of shrimp as they grow is reduced by sorting by size. The daily diet varies, depending on age, from 100 to 50% of the weight. Planting material weighing at least 1 g can be used for growing in intensive conditions (closed water supply systems).

Water quality

The optimal temperature for this species is from 26 to 30 °C. Although they can live at temperatures from 22 to 32 degrees, growth will be poorer and the shrimp will be lethargic.

Optimum pH 7.2-8.4. If the pH is below 7.0, the shrimp will have trouble hardening their shells after molting. An infection can penetrate under a weak shell.

Regular water changes are also necessary. However, shrimp are very sensitive to chlorine. Tap water must be allowed to settle before adding.

Good aeration is very important. Although these shrimp tolerate low amounts of oxygen in the water for short periods of time, when oxygen is deprived for a long time, the shrimp lose their appetite, become less active and at the same time more aggressive towards their comrades. Apparently, by killing the inhabitants in the aquarium, they are trying to get rid of competitors for oxygen.

Requirements for an artificial reservoir

When equipping shrimp tanks, it is important to adhere to the following rules:

pool depth is at least 1 meter;
the more spacious the container, the better (you should start from 1 ton);
The material of the pool is not of fundamental importance (concrete, plastic, PVC);
The bottom of a false reservoir must be equipped with original shelters where shrimp can hide from their relatives, because There are frequent cases of eating each other.
It is enough to throw available materials to the bottom - pipe scraps, slate, bricks, branches, stones.

Diseases

Most often, Rosenberg shrimp suffer due to damage to the shell during combat or due to improper handling, which can lead to infection. Damage to the shell can be repaired during molting. In addition, broken antennae, claws, and limbs are also restored during molting.

The second common disease is loss of pigmentation. The color on the entire body disappears and the shrimp remains transparent. This can happen even in a dark aquarium. This is usually associated with poor nutrition. More varied food - and everything will return to normal.

The third problem is the “death molt” syndrome. During molting, the shrimp is unable to remove its claws, legs or other body parts from the old shell. The new exoskeleton either does not harden or is irregularly shaped. This usually results in the death of the shrimp. Recent research indicates that this syndrome may be a consequence of low levels of soy lecithin in the diet. These results highlight the importance of proper shrimp nutrition.

Sex differences

In macrobrachiums, sexual differences are pronounced. Males have a larger body and claws, a tapering, darker cone-shaped tail. In females, the belly is wider, the segments protecting the eggs are lowered.

A secondary sign of how to determine gender is behavior. Males are more active and pugnacious. Constant fights for territory lead to the fact that out of 20 adult males, only 2-3 have healthy claws. For most, they are either injured or completely torn off.