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What operating techniques are needed to culture fresh shrimp in crab ponds?

The mixed culture of freshwater shrimp and river crab can make full use of pond water and feed, and obtain a double harvest of shrimp and crab without basically increasing labor intensity, greatly improving the overall economic benefits of pond aquaculture.

(1) Pond preparation

① Pond selection: The pond for mixed culture of shrimps and crabs should be of unlimited area, with a water depth of 1 to 1.5 meters, a bank slope of about 1:3, no seepage or leakage, convenient drainage and irrigation, sufficient water source, fresh water quality, rich dissolved oxygen in the water, and no industrial or domestic sewage pollution.

② Pond cleaning and disinfection: The breeding ponds are required to remove excess silt and be exposed to sunlight in winter. Half a month to one month before stocking, 75-100 kg/mu of quicklime should be used to make a slurry, or 20 grams of bleaching powder per cubic meter of water should be sprayed throughout the pond to kill wild fish and improve the pond bottom quality.

③ Anti-escape facilities: Anti-escape facilities are built around the pond, usually with a 0.5-meter-high aluminum foil, plastic film or plastic board circle inserted 0.2 meters into the soil. Leave a slope of more than 1 meter in the anti-escape facility to facilitate breeding and management, and have sufficient area for river crabs to move. During the entire breeding process, the water inlet is filtered with a 60-80 mesh nylon silk mesh bag to prevent wild fish and fish eggs from entering the pond; a fine mesh net is installed at the drain outlet to prevent the shrimp from escaping.

④ Transplant aquatic plants: At the beginning of the year, plant or transplant aquatic plants such as Elodea, water peanut, water spinach and water lily along the shallow water belt 1 meter away from the edge of the pond. The width of the grass belt should be about 1 meter. The area of ​​aquatic plants should be controlled to account for 25% of the total pond area when they are growing vigorously. Excess aquatic plants should be manually cut off.

(2) Stocking of seedlings: 400-600 one-year-old crabs or 1,000-1,200 bean crabs per mu, and 40,000 shrimp seedlings. The crabs and shrimp seedlings to be stocked must be of pure species, uniform in size, with complete appendages and free of disease. The stocking of one-year-old crabs should be avoided during the cold winter, and bean crabs should be stocked as early as possible to increase the size of adult crabs out of the pond. In addition, 60 one-year-old silver carp and bighead carp per mu are stocked in the pond. Stocking filter-feeding fish can not only make full use of pond bait organisms, significantly improve water quality, and reduce the outbreak of blue algae and green algae in the hot season, but also reduce the number of autumn shrimp seedlings, control the stocking density, and increase the market size, thereby achieving the goal of increasing production and efficiency.

(3) Feed and feeding In the early stage of feeding, pellet feed and animal feed, such as snails, clams, cockles, small fish, etc., are mainly fed, supplemented with a small amount of aquatic plants, which can not only meet the nutritional needs of shrimps and crabs, but also avoid or reduce cannibalism and reduce production costs; during the middle period of high temperature, increase the amount of plant feed; in the later stage, increase the amount of animal feed to ensure the growth and fattening of river crabs. The particle size of pellet feed is 1.5-2.2 mm, and the crude protein content is 35%-40%; animal feed should be crushed. Feed twice a day, of which the amount fed in the morning accounts for 1/3 of the daily feeding amount, and the amount fed in the afternoon accounts for 2/3 of the daily feeding amount. The daily feeding amount of pellet feed is controlled at 3%-5% of the body weight of shrimps and crabs, and the feeding amount of fresh bait is 10%-15% of the body weight of shrimps and crabs. Feed should be evenly distributed to the water grass belt about 1 meter away from the edge of the pond. The daily feeding amount should be flexibly controlled according to the amount of shrimp and crab in the pond and their growth conditions, water temperature, weather and other conditions. It is necessary to avoid wasting feed and spoiling water quality, and to ensure that shrimp and crabs eat enough to meet their growth needs, and not feed spoiled feed. In order to facilitate the inspection of feeding conditions, several feeding tables can be set up around the pond for observation. Generally, it is considered that the shrimp and crabs basically finish eating within 1 to 2 hours.

(4) Water quality control During the entire breeding process, the water quality of the pond should always maintain an appropriate fertility and transparency of 25 to 30 cm. Generally, the water level is maintained at 0.6 to 0.8 meters in the early stage of stocking to facilitate temperature rise; in the middle and late stages (especially in late autumn and winter), the water level is raised to 1 to 1.5 meters to facilitate heat preservation during the winter. Fill and drain water in a timely manner, and flexibly adjust the water level according to the season and temperature to maintain a relatively suitable water temperature for the growth of shrimps and crabs. Normally, add new water once every half a month to one month, and increase the water change to once every 5 to 7 days during the high temperature season from July to September. Drain the old water in the lower layer before injecting new water, and inject 0.2 to 0.3 meters of water each time. Sprinkle quicklime once every 10 to 15 days, 5 to 10 kg/mu each time, to increase calcium, improve water quality, and meet the growth needs of shrimps and crabs.

(5) Daily management: Patrol the pond every morning and evening. In hot and humid weather, patrol the pond at night and carefully observe the activities, feeding, molting, diseases and escape prevention facilities of fresh shrimp and river crabs. In summer and autumn thunderstorms, fresh shrimp and silver carp are prone to floating, so special attention should be paid.

(6) Disease prevention and control Disease prevention and control of shrimp and crabs should start with the quality of seedlings and water quality, and achieve "prevention is the main thing, and prevention is more important than treatment." Maintaining good water quality in the pond, regularly spraying quicklime, and feeding high-quality, fresh feed can generally prevent the occurrence of diseases.

(7) River crabs can be caught and marketed in October and continue to be available until around the Spring Festival. They can be caught by hand near the pond or by catching them when the pond is dry. Prawns are available between New Year's Day and the Spring Festival. They are caught with a scoop net and then by catching them when the pond is dry. Small-sized prawns can be farmed and marketed the following year depending on market conditions.

This article is from: China Agricultural Press "China Biotechnology Development Report"

What are the techniques for catching small river shrimp?

The method of catching shrimp using a shrimp trap. You will need:

1. The bait includes 30g wild fish meal, 30g loach meal, 35g fresh chicken blood meal, 60g plant green flavor powder, 45g fishy flavor powder, 35g puffed powder, 15g MSG, 55g appetite promoter powder, 50g asafoetida, and 70g animal bone meal; take the above substances in proportion, put them into the dryer respectively, dry them, crush them into particles, and mix them;

2. Cage: The shrimp cage has a cage with a whisker opening and a shrimp taking door on the side of the cage. The whisker opening is connected to the whisker, and a bait column is connected inside the cage. The cage has a bracket, which forms a rectangular parallelepiped. The bracket is wrapped with a mesh, and has two whisker openings on the end face of one end, and a whisker opening and a shrimp taking door on the other end face. There is a whisker pull line on the whisker opening connected to the bracket.

The shrimp catching method has a simple shrimp cage structure and low cost; the trapping effect is good and the trapping rate is high, reaching 98%, and the life pattern and normal growth of shrimps are not affected; shrimp catching is not restricted by the terrain and water surface in the water area, and the labor intensity is low.