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How to breed high quality crabs in ponds
In order to cultivate high-quality crabs in ponds, in addition to the selection of water areas and pond sites, rational planning, design of crab ponds, and good anti-escape facilities, we must also focus on the following six key technologies. First, clear pond disinfection. Combined with winter dry pool repair, remove excess silt, leave silt about 10 centimeters, freeze and dry for 10-20 days, use quicklime Quanchiposa, use 200-250 kg per acre, remove impurities, remove pathogens, improve Substrate. Second, planting aquatic plants and transplanting snails. Water plants and snails are excellent natural bait for crabs, especially aquatic plants, which is the key to the success of breeding. “To raise a pond crab, we must first plant a pond grassâ€. Planting time is generally before and after Qingming, the depth of water is controlled at about 20 cm, and the varieties planted are mainly black-leaf algae, Vallisneria, Elodea, etc. Some water peanuts can also be set to ensure that the coverage of aquatic plants reaches 70% or so. To shade, increase the role of habitat. Before and after Qingming, 200-300 kilograms of live snails were placed per acre, allowing them to reproduce and multiply naturally. Their young snails are thin, tender and tender, which is a peculiar natural food for juvenile crabs, and can also play a role in water purification. Third, crab species stocking. The crabs should be stocked with “three types of fitness†and “a temporary raise,†namely, appropriate density, appropriate specifications, timely stocking, and stocking after temporary rearing. The species of crabs in the Yangtze River system is selected as the crab species, and the specifications are neat, and the appendages are complete. The disease is disease-free and injury-free. In particular, crabs cultivated in local ponds are suitable. The stocking rate per mu is between 500 and 600. The stocking specifications are preferably 100-200 kg/kg, and the specifications are too large. The first time the clamshell is difficult, and the damage is large; if the specification is too small, the growth base is not large, and the market specification is affected. In stocking time, one stock is from late February to March. If stocking is too early, the casualties during the overwintering process will be large; if it is too late, the temperature of the water will rise, and some crabs will crust, which will affect the survival rate of the lower pond. The preservation of crab species is a transitional stage before the stocking of crab species. Before stocking, set up a "holding zone" in the pool. The duration of the holding period depends on the water temperature and the growth condition in the pool. The holding area accounts for about 1/5 of the stocking area. Fourth, feed feeding. Cave crabs are omnivorous animals of partial animal feed. Basing on the cultivation of basic baits, we must actively do a good job of feeding by hand, and adhere to the principles of "Four-definition" and "Four-seeing" scientific feeding methods and the "before and after refinement, middle-greenness, and meat quality matching". Each shot in the morning and evening, feeding the amount of 1-2 hours is appropriate, and often check the food market, timely adjustment of the amount of feeding. In the initial stage of stocking, mainly animal feeds, mainly fresh fish, snail meat, etc., gradually increase the feeding of plant concentrates, such as wheat, corn, soybean meal, etc., in the hot season, do not cast animal food, less investment For plant-based concentrates, increase the feeding of green roughage, such as pumpkins, potatoes, etc., and enter the later stage of cultivation (the stage of crabs promotes weight gain and weight increase), then increase plant-based concentrates and animal foods to ensure that the crabs eat well. In the feeding management of the whole year, the key points are to close two good oyster shells and carefully feed palatability and nutrient feed to ensure the survival rate of crabs and the listing rate of large-sized crabs. Fifth, water quality regulation. Water is the root of culture. Water quality regulation is another important link in ponds and crabs. It mainly focuses on four aspects: First, the water level is controlled, the general water depth is kept at 0.5-0.8 meters, and the mid-aquaculture temperature is high, and the water depth is controlled at 1.2 meters. It will help reduce the water temperature and promote the growth of river crabs. Second, it will frequently change the water, generally changing the water once every 7-10 days. During the high temperature period, it will inject water 10-20 centimeters per day, change the water once every 3-4 days, and change the water. The method of rear row; the third is to adjust the pH. 7-10 days Quanchiposa lime, a dose of 10-15 kg per acre, to ensure that the PH of the water between 7.0-8.5, while increasing the content of calcium in the water, clearing and purifying water quality; Fourth is not regular splash " "Active enzyme" (0.4-0.6 kg per acre) to transform and absorb harmful substances such as ammonia nitrogen and hydrogen sulfide in water to control the breeding and breeding of harmful bacteria. Six, crab disease prevention and treatment. Disease prevention and control of river crab follows the principle of “prevention first, prevention and control combined†and actively adopts highly effective, low-toxic, and side-effect drug control. The main drugs used are lime, carapace net, crab multidimensional, biological preparations, and Chinese herbal medicines, etc. Crab constitution, disinfection of water bodies, control and prevention of bacterial diseases and viral diseases, disease early treatment, disease-free early prevention, to minimize the disease.