Detailed Explanation of Key Technical Points for Crayfish Cage Culture

Preparation Before Stocking

The pond must have good water inlet and drainage facilities. Around the pond, a 50 cm high escape-prevention wall should be built with bamboo strips, mesh gauze, etc. Set up shrimp habitats in the culture water area, such as installing tiles, bricks, stones, mesh sheets, old tires, grass bundles, etc. as shrimp nests, for the shrimp to hide and rest and to defend against enemies. Plant water hyacinth, alligator weed, water lettuce, wild rice stem and other aquatic plants around the inside of the pond, with a coverage area generally 1/3 of the pond water surface, to facilitate shading for the crayfish and to 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 for crayfish culture, it is necessary to remove silt, repair and level it, and expose it to the sun. 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 water surface of fully decomposed manure such as pig manure, to cultivate plankton and provide an appropriate amount of organic debris as shrimp feed. Before water is let into the pond, install the water barrier net, preferably 60-80 mesh, to prevent enemies in the water from entering. Keep the pond water depth at 50-80 cm, with transparency between 30-40 cm.

Stocking Shrimp Fry

Stocking shrimp fry is best done on sunny mornings and evenings, stocking 6000-8000 young shrimp 2 cm long per mu, or 4000-6000 young shrimp 3-5 cm long. The specifications of shrimp fry stocked in the same pond are required to be uniform and consistent. At the same time, 300-400 silver carp and bighead carp of about 50 g and 200 bream may be stocked in the pond water.

Careful Feeding

Within 3 days after stocking, feed minced small fish and minced meat; from 3 days to 1 month after, feed small trash fish, offcut minced meat or compound feed; when the shrimp fry grow to 6-7 cm, all can be fed crushed snails, river mussels and an appropriate amount of plant-based feed such as wheat, bran, corn, cake meal, etc. or compound feed. The daily feeding amount is based on eating full, 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, which can be adjusted specifically according to the shrimp's feeding situation. Feed twice a day, once in the morning and once in the evening, with the evening feeding amount accounting for 70%-80% of the daily feeding amount. The bait should be placed around the pond and appropriately scattered, with a bit more where crayfish are concentrated, to facilitate their feeding.

Water Quality Management

Crayfish grow quickly, have vigorous metabolism and consume a large amount of oxygen, so the pond water quality must be kept fresh. Add water 15-20 cm deep every week to ensure the water quality is fresh and clean and has sufficient dissolved oxygen. Keep the 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 in severe weather such as thunder showers, muggy days and consecutive cloudy days, reduce the feeding amount or stop feeding, and pay attention to observation. If the crayfish are found to be slow to respond, gathering at the shore, floating at the surface and climbing onto the shore, it indicates severe oxygen deficiency, and water should be added in time or an aerator turned on to increase oxygen.

Disease Prevention

Check frequently and patrol the pond frequently, paying attention to the crayfish's foraging, activity, growth and molting, so as to take necessary technical measures in time. Remove moss in the pond in time; often check the filter nets at the water inlet and outlet to prevent the crayfish from escaping or harmful organisms such as wild trash fish from entering due to broken filter nets. Always pay attention to whether there are enemy organisms in the pond, such as water rats, water snakes, water birds, etc., and remove them in time if present.

Before the 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 new water, keep the pond water clean and hygienic, and add multiple vitamins to the shrimp feed to enhance the shrimp's immunity.

Timely Harvesting

Generally after about 2 months of rearing, when the crayfish reach a body weight of more than 50 g, they can be harvested for market. Crayfish are harvested by methods such as shrimp cages, ground cages and surround nets, harvesting the large and retaining the small.