Detailed Explanation of Key Technical Points for Polyculture of River Crab and Freshwater Shrimp

1. Pond conditions. The pond area should preferably be 3-8 mu, with abundant water sources, fresh and pollution-free water quality; equipped with aerators or water pumps and other fishery machinery; inlet and outlet are fitted with escape-prevention nets. Conduct pond cleaning and renovation in winter, using 100-150 kg of quicklime per mu for thorough disinfection.
2. Planting grass and introducing snails. Plant aquatic plants in the pond around the Spring Festival, requiring a summer aquatic plant coverage rate of 60-70%; put in 300-400 kg of disinfected snails per mu.
3. Seedling stocking. The stocking time for freshwater shrimp seed is from December to February of the following year, with a size of 800-1,000 tails/kg, stocking 20,000-25,000 tails per mu; the stocking time for crab seed is from February to March, with a size of 120-160 individuals/kg, stocking 600-700 individuals per mu; freshwater shrimp fry are stocked in early to mid-July, with a size of 12,000-16,000 tails/kg, stocking 50,000-70,000 tails per mu. Seedlings are required to be disease-free and injury-free, and stocked after disinfection.
4. Feed feeding. Feed feeding follows the principles of “fine at both ends, coarse in the middle” and “matching meat with vegetables, combining green with fine”, while flexibly adjusting according to weather, water temperature, water quality and the feeding situation of the cultured species. The protein content of the feed is required to be above 35%.
5. Water quality regulation. Regularly or irregularly add fresh water or exchange water; every 15-20 days, splash quicklime slurry over the whole pond; regularly splash biological preparations mixed with water over the whole pond; keep the pond water transparency at 30-40 cm.
6. Disease prevention and control. Follow the principle of “prevention first, combining prevention with control”, and strictly prohibit the use of banned drugs.
7. Daily management. Patrol the pond every morning and evening, mainly observing changes in water color, the activities, feeding and molting conditions of the cultured species, checking the feeding platform, promptly removing residual bait or debris, preventing water quality deterioration, and keeping records of daily management, feeding, water quality management, disease prevention and control, etc.
8. Harvesting time. Spring shrimp harvesting begins in April, autumn shrimp harvesting begins in September, and river crabs begin to be harvested at the end of September according to market conditions, implementing the method of harvesting large ones and keeping small ones.
9. Key management points. (1) Pond clearing must be thorough. (2) Do not use any fishery drugs during the molting period of shrimp and crabs. (3) Strictly prevent aquatic plant decay during high-temperature seasons. (4) Harvest in a timely manner.
10. Benefit analysis. Generally, the yield per mu is 80-90 kg of river crab and 50-60 kg of freshwater shrimp, with an output value per mu of about 9,000 yuan. After deducting the production cost of 3,500-4,000 yuan per mu, the benefit per mu is 5,000-5,500 yuan.