Crayfish Fry Breeding Techniques and Purchasing Channel Introduction

The crayfish's body shape closely resembles that of a shrimp, and its carapace is extremely hard. Moreover, the crayfish has very strong adaptability. Especially during its breeding period, it particularly likes to dig burrows. The crayfish is an omnivorous animal. It likes to eat the mud at the bottom of the water, or small fish that have already died. So how should the crayfish be bred? Let us take a look together.

Crayfish Fry Breeding Techniques

1. Selection of Parent Crayfish

Parent crayfish can be selected in September-October of the previous year or March-April of the current year, requiring a body weight of 30-50g, complete appendages, healthy and disease-free, strong activity, and a female-to-male ratio of 2-3:1. Male and female crayfish have obvious features in appearance and are easy to distinguish. In sexually mature crayfish, males are noticeably larger than females; male crayfish have thick and large legs, with a bright red soft wart on the outer side of both ends of the legs, while female crayfish have relatively smaller legs, and most female legs have no red soft wart, and even if present, the color is lighter; male crayfish have thick and large legs, with a bright red soft wart on the outer side of both ends of the legs, while female crayfish have relatively smaller legs, and most female legs have no red soft wart, and even if present, the color is lighter; the male genital pore opens at the base of the 5th pair of walking legs, while the female genital pore opens at the base of the 3rd pair of walking legs; sexually mature female crayfish have a swollen abdomen, while the abdomen of male crayfish is relatively narrow.

2. Parent Crayfish Breeding

1. The area of the parent crayfish pond is preferably around 1200 sq m, the bottom substrate is preferably loam, the water depth is around 1m, the pond ridge width is more than 1.5m, there is an adequate and good water source, water inlet and drainage outlets are built, and the pond ridge around is built with plastic film or calcium-plastic board as an anti-escape wall. 7-10 days before stocking, the pond is disinfected with 50-60kg/mu of quicklime for dry pond disinfection. After disinfection, water is injected through filtration (to prevent wild fish from entering the pond) to a depth of about 1m, and 500-800kg/mu of decomposed livestock and poultry manure is applied to fertilize the water quality. Hidden objects for crayfish to climb and inhabit are placed in the pond, such as branches, tree roots, bamboo tubes, etc., and some aquatic plants are transplanted.

2. The parent crayfish pond can be stocked with 40-60kg/mu of parent crayfish, soaked in 3% salt water for 10 minutes before stocking to kill pathogens. To make full use of the water body and regulate water quality, silver carp and bighead carp can be polycultured at 50-100 fish/mu. During the breeding period, fresh aquatic plants, soybean cake, wheat bran or compound feed can be fed, and a portion of animal feed can be added. Such as chopped snail and mussel meat, livestock and poultry slaughtering scraps, etc. Daily feeding amount: 2%-3% of the parent crayfish body weight in March, 4%-5% in April, 6%-8% after May, fed once each in the morning and evening every day, mainly in the evening, accounting for 70% of the daily bait amount. At the same time, strengthen water quality management, change new water once every 10-15 days, changing 1/3 each time; every 20 days, splash 10-25g/sq m of quicklime mixed with water once, to maintain good water quality and promote the gonadal development of parent crayfish.

3. Parent Crayfish Reproduction

In April-May, when the water temperature is above 20, the parent crayfish begin to mate. Fertilized eggs hatch into young crayfish in the female's abdomen, and the hatching time takes 40-70 days. After hatching, the young crayfish complete the growth and development process of the juvenile stage under the protection of the mother. As soon as the young crayfish leave the mother, they can actively feed and live independently. When a large number of young crayfish are found in the breeding pond, seedlings should be collected in time for fry breeding.

4. Parent Crayfish Overwintering

The minimum survival water temperature for crayfish is 5°C. But when the water temperature is below 9°C, crayfish about 3 cm long have a very high mortality rate during overwintering, and although adult crayfish can survive, a large number will also die after 2-3 months. Therefore, doing a good job in the overwintering of parent crayfish and ensuring that the water temperature during overwintering is 16°C-18°C is also an important part of the entire breeding work. Commonly used overwintering methods include the plastic film pond covering insulation method, electric heater heating method, hot spring water overwintering method, factory waste heat water overwintering method, and glasshouse overwintering method, etc., all of which can achieve the effect of safe overwintering of parent crayfish.

5. Fry Breeding Techniques

Although crayfish do not carry a large number of eggs, the fertilization rate can be above 98%, and the hatching rate can reach 80%-85%. The problem is that after emergence, the juvenile crayfish grow and molt frequently, and are extremely susceptible to environmental conditions, which affects the fry breeding rate.

Where to Buy Crayfish Fry

Crayfish have strong adaptability and can be raised in most areas of the country, so they can be purchased according to the principle of proximity, combining local and non-local fry. In rice field crayfish farming in the same area, long-term self-breeding and self-raising leads to multi-generation inbreeding, weakening of genetic genes, and the emergence of premature maturity, small individuals and other germplasm degradation phenomena, with weak disease resistance and susceptibility to various diseases. Therefore, appropriately screen and introduce some fry from other places (preferably outside the province). Introduce fry early. Start introducing fry at the end of March each year, so that crayfish can adapt to the breeding environment early, feed early, and reach market size early. The introduced fry should be larger in size, with a high survival rate, short breeding cycle, and quick results. The fry introduced in the same batch should be neat in size and complete in limbs. Experiments have shown that during winter fry breeding, using biological fertilizers and biological feed to breed fry can achieve the purpose of early fry emergence, neat size, and robust physique.

What Crayfish Need to Do Well to Improve the Fry Breeding Rate

1. Water quality requirements: during the crayfish breeding period, the water body should be kept relatively stable, the water quality fresh, and the pH value between 6.5-8; prevent excessive temperature differences between day and night; the dissolved oxygen in the water should be maintained above 5.6 mg/L.

2. Water body environment: there must be water hyacinth on the water surface (accounting for 1/3), preferably aquatic plants at the bottom, and hidden burrows, to increase the attachment objects for fry molting, and also facilitate checking the emergence time and crayfish growth through washing seedlings with water hyacinth. Add fences and filter nets at the water inlet to prevent harmful organisms from entering the pond, and at the same time prevent frogs from entering the pond to lay eggs, avoiding tadpoles preying on fry. At the same time, prevent parent crayfish from climbing and escaping.

3. Strengthen inspection: insist on checking the emergence situation in the morning and evening. When the juvenile crayfish leave the mother, promptly catch the parent crayfish and return them to the parent crayfish pond for re-breeding, minimize counting and transferring between ponds, and handle with special care to avoid affecting the egg-carrying parent crayfish and newly hatched juvenile crayfish.

4. Ensure feed supply: timely cultivate small zooplankton such as rotifers for the newly hatched juvenile crayfish to feed on. An estimated 3-5 days before emergence, start catching a small amount of small zooplankton from the special feed pond into the fry pond. And use cooked egg yolk, soybean milk, etc. to timely supplement the food supply needed by juvenile and young crayfish.

Crayfish Disease Management

1. Vibrio Problem

As the water temperature rises above 30°C, the crayfish white spot syndrome virus disease disappears. However, Vibrio does not disappear. As the temperature rises, the bottom temperature is relatively low first, and the bottom oxygen is also relatively low. This environment is more suitable for the growth of Vibrio. Crayfish will show a small amount of death or sluggishness.

2. Solution

1. For ponds that continue farming, it is recommended to regularly improve the bottom, reduce oxygen-consuming substances at the bottom, and indirectly increase dissolved oxygen at the bottom.

2. Thoroughly clean the pond, use quicklime or bleaching powder, strong chlorine, and other pond-clearing drugs to kill pathogenic microorganisms in the pond, fundamentally reducing harmful bacteria and viruses.

However, because crayfish have very strong pollution resistance. So we can put it in an aquarium, and it can also effectively remove fish excrement or moss. Moreover, the protein content in the crayfish body is very high, so it can also be given to people with weak health.