Detailed Explanation of Key Technical Points for Crayfish Cage Culture

With the continuous development of the aquaculture industry today, many people have begun to farm crayfish one after another. There are many methods for farming crayfish, and today the editor wants to introduce to you cage culture of crayfish. In the aquaculture industry, only by keeping pace with the steps of social development and adopting the latest farming techniques can work be saved and effort reduced.

Techniques for Farming Crayfish in Cages

 I. Preparation Before Stocking

The pond must have good water inlet and drainage facilities. Around the pond, bamboo strips, mesh gauze, and similar materials should be used to enclose an anti-escape wall 50 cm high.

Set up shrimp habitat sites in the farming water body, such as installing tiles, bricks, stones, mesh sheets, old tires, grass bundles, and so on as shrimp nests, for the shrimp to hide, rest, and defend against enemies. Around the inside of the pond, plant aquatic plants such as water hyacinth, alligator weed, water lettuce, and wild rice stem, with their coverage generally at 1/3 of the pond water surface, to help shade the crayfish and breed the plankton that crayfish like to eat. Generally, for newly built crayfish ponds, quicklime water can be used to clear the pond with water present, using 100 kg per mu. If an old pond or lake is used to farm crayfish, it must be desilted, repaired, and sun-dried. 10-15 days before stocking shrimp fry, use 50 kg of quicklime per mu for dry pond disinfection. At the same time, thoroughly eliminate predatory wild enemies in the pond such as catfish, loach, snakehead, snakes, and rats.

10-15 days before stocking shrimp fry, generally apply 100-200 kg per mu of fully decomposed manure such as pig manure to the water surface, to cultivate plankton and provide an appropriate amount of organic debris as shrimp feed. Before water is let into the pond, install a water barrier net, preferably 60-80 mesh, to prevent underwater enemies from entering. Keep the pond water depth at 50-80 cm, with transparency between 30-40 cm.

II. Stocking Shrimp Fry

Shrimp fry should preferably be stocked on clear mornings and evenings, with 6,000-8,000 young shrimp 2 cm long per mu, or 4,000-6,000 young shrimp 3-5 cm long. The specifications of shrimp fry stocked in the same pond should be neat and consistent. At the same time, 300-400 silver carp and bighead carp of about 50 g and 200 bream can be stocked in the pond water.

III. Careful Feeding

Within 3 days after stocking the fry, feed minced small fish and minced meat. From 3 days to 1 month afterward, feed small miscellaneous fish, scrap minced meat, or compound feed. When the shrimp fry grow to 6-7 cm, they can be entirely fed crushed snails, river mussels, and an appropriate amount of plant-based feed such as wheat, bran, corn, oilseed cakes, or compound feed. The daily feeding amount should be based on eating enough, finishing the food, and leaving no residual bait. Generally, for medium and small crayfish, feed 15%-20% of body weight, and for adult shrimp, feed 5%-10% of body weight. The specifics can be adjusted according to the shrimp's feeding situation. Feed twice a day, once in the morning and once in the evening. The evening feeding amount should account for 70%-80% of the daily feeding amount. Bait should be placed around the pond and properly dispersed, with a bit more placed where crayfish are concentrated, to facilitate their feeding.

IV. Water Quality Management

Crayfish grow quickly, have vigorous metabolism, and consume a large amount of oxygen, so the pond water quality must remain fresh. Add water to a depth of 15-20 cm each week to ensure the water is fresh, clean, and has sufficient dissolved oxygen. Keep pond water transparency above 35 cm deep. When the weather is too hot, appropriately deepen the pond water to stabilize the pond water temperature. Strictly prevent water quality from being polluted by industrial pollution, pesticide pollution, and chemical pollution.

When dissolved oxygen in the water is low, the water quality is aging, or there is severe weather such as thunderstorms, muggy days, or continuous overcast days, reduce the feeding amount or stop feeding, and pay attention to observation. If crayfish are found to react slowly, gather at the bank, float at the surface, and climb toward the shore, it indicates severe oxygen deficiency, and water should be added promptly or an aerator turned on to increase oxygen.

V. Disease Prevention

Check frequently and patrol the pond frequently, paying attention to crayfish foraging, activity, growth, and molting, so that necessary technical measures can be taken in time. Promptly remove moss from the pond; often inspect the filter nets at the water inlet and outlet to prevent crayfish from escaping or harmful organisms such as wild miscellaneous fish from entering due to broken filter nets. Always watch for whether there are harmful organisms in the pond, such as water rats, water snakes, and water birds, and remove them promptly if present.

Before shrimp fry are put into the pond, their body surface must be disinfected to prevent pathogens from being brought into the pond. Regularly disinfect the shrimp pond with quicklime, frequently add fresh water, keep the pond water clean and hygienic, and add multiple vitamins to the shrimp feed to enhance the shrimp's immunity.

VI. Timely Harvesting

Generally after about 2 months of rearing, when crayfish reach a body weight of more than 50 g, they can be harvested for market. Crayfish are harvested using shrimp cages, ground cages, seine nets, and other methods, catching the large and leaving the small.

Market Prospects for Crayfish  

Crayfish, scientific name Procambarus clarkii, has strong adaptability to the environment, few diseases, tolerance to low oxygen, and can grow and reproduce in water bodies such as ponds, river ditches, lakes, rice fields, and swamps. It can also remain out of water or live in burrows for a relatively long time, has strong tolerance to adverse environments, is convenient to transport, and has a high transport survival rate. This is unmatched by other shrimp species. At the same time, crayfish seedlings are easy to breed and can be self-bred and self-raised, without needing complex equipment. The technology is simple, feed is easy to solve, and it is suitable for artificial farming. Generally, intensive pond culture yields 400 kg per mu and profits of more than 1,600 yuan.  

At present, the amount of artificially farmed crayfish is small, and the market mainly relies on wild capture, with its natural resources far from meeting the consumption demand of international and domestic markets. European and American countries are the main consumers of crayfish. In the United States, this shrimp is not only an important edible shrimp but also an important bait for angling, with annual consumption of 60,000-80,000 tons, and self-sufficiency of less than 1/3. The European Union and the United States import up to 20,000 tons from China each year. Sweden is even a fanatical consumer of crayfish, holding a 3-week crayfish festival every year. The Western European market consumes 60,000-80,000 tons of crayfish a year, while Western Europe's self-sufficiency accounts for only 20% of total consumption. 

Living Habits of Crayfish  

Crayfish are nocturnal animals that live by crawling along the bottom. They inhabit lakes, rivers, reservoirs, swamps, ponds, and ditches, and are sometimes also seen in rice fields. However, they are more common in still-water ditches, ponds, and shallow lakes with relatively abundant food. Their habitat is mostly soil, with more aquatic plants, tree roots, or stones and other hiding objects. During the day, they often lurk in darker corners at the bottom of the water, beside stones, in grass, or in burrows, and come out at night to feed. Under natural conditions, because of lack of bait and low water transparency, they can also be seen foraging during the day. This shrimp has strong climbing ability and burrowing ability.  

When the water body lacks oxygen, lacks bait, is polluted, or when other biological, physical, and chemical factors change drastically and become unsuitable, they often climb out of the water and enter another water body. For example, when it rains, especially when it rains heavily, this shrimp often climbs out of the water body to move about. During the growth period, crayfish basically do not dig burrows. The longest crayfish burrow can reach 100 cm, with a diameter of up to 9.2 cm. Crayfish can use artificial burrows, original burrows in the water body, and other hiding objects, and their burrowing behavior mostly appears during the breeding period. Therefore, appropriately adding artificial nests in the farming pond and applying technical measures can greatly reduce the destructive effect of this shrimp on pond ridges and embankments.

Latest Crayfish Farming Techniques  

I. Low investment, quick results. Crayfish have 2 spawning periods each year, one in autumn and one in spring. A pair of male and female crayfish can breed up to 480 shrimp fry at one time. Usually, crayfish that come to market in early spring are shrimp fry bred in the previous autumn, while shrimp fry bred in spring only need to be farmed for more than 50 days before they can be marketed. In the first year, crayfish farmers only need to keep the large whole-clawed crayfish as breeders. By autumn, the crayfish will dig holes and enter them to give birth, and in the second year there is no need to buy too many crayfish seedlings. Because crayfish like to dig holes, the embankments for low-ridge, high-enclosure, and inner-pond crayfish farming must be at least 5 m wide, and the enclosure net must also be buried 2 m deep to prevent crayfish from escaping.  

II. Big appetite, mixed feeding habits. Crayfish like to live in water areas with alligator weed and wild rice stem. In crayfish ponds, a lake ecological environment can be simulated, and some wild rice stem and alligator weed can be planted. First, in summer this can provide shade and prevent crayfish from maturing early; second, it can breed the plankton that crayfish like to eat. Crayfish have a very good appetite, and various wild miscellaneous foods such as wheat and corn are all good feed for them. Crayfish are crustaceans, and they grow larger each time they molt, so new water should often be added to the pond to help crayfish molt and grow.  

III. Not afraid of dirty, smelly water, but afraid of chemicals. Crayfish are not afraid of dirty, smelly water, but they are very sensitive to chemicals such as pesticides, chemical fertilizers, and liquefied petroleum gas. As long as these chemicals are present in the pond, the crayfish will all die out. Adopting the following “eight-character formula” can improve crayfish farming yield and benefits. 

There are many techniques for farming crayfish. Farmers can reasonably choose a farming method that suits them according to their own circumstances. Although the investment costs required by different farming methods may differ slightly, the ultimate result hoped for is to obtain high yields of crayfish. In fact, method is one aspect, and the farmer's own effort is equally important.