Disease control: shell rot? The toes of the sick crab were damaged and turned into black ulcers, and then white spots appeared on each foot joint, carapace and chest plate, and gradually became black ulcers. In severe cases, the carapace is eroded into a hole, and muscles or skin membranes can be seen, resulting in the death of crabs. This disease is caused by toe damage and bacterial infection of crabs. ? Precautionary measures: thoroughly clean the pond with quicklime, keep the water clean, often replenish fresh water in summer, and keep 5- 10 cm silt at the bottom of the pond. In the pond with symptoms, the whole pond is splashed with quicklime mixed with water, showing 15-20 ppm. Treatment: 2PPM bleach was sprayed in the whole pond, and sulfonamides were added to the feed, with 0. 1-0.2 g per kg feed for 3-5 days. The gill of black gill disease crab is infected and discolored. When it is light, the left and right gill filaments are dark gray or black. When it is heavy, all the gill filaments turn black. Sick crabs are slow to move and have difficulty breathing, commonly known as sigh disease. The disease mostly occurs in the late stage of adult crab culture, and the deterioration of water environment conditions is the main cause of the disease. Prevent the same rot. The crab's abdomen and appendages are rotten. During the wintering period, the incidence of the disease is high, and the appendages rot, and the spots change from yellow to gray and then to black. This disease is caused by being injured by enemies during fishing, transportation and stocking or being infected by bacteria during growth. ? Caution: Do not harm crabs during fishing, transportation and stocking. ) Before stocking, the crab was soaked in 2PPM furazolidone solution for several minutes, and then released. Treatment: 0.5-1ppm of oxytetracycline or furacilin in the whole pool; Furazolidone overflowed from the whole pond was 0.1-0.2 ppm; The quicklime is sprinkled in the whole pond in the form of 15-20 ppm, and applied in 2-3 times. Edema: The abdomen, navel and the lower part of the back shell of the sick crab are swollen. The sick crab climbs to the edge of the pool, refuses to eat, and finally dies in the shallow water near the pool. This disease is caused by abdominal injury and infection of Eriocheir sinensis during culture. ? Preventive measures: In the process of breeding, especially when molting, try to reduce the disturbance to the river crab and avoid its injury. Treatment: 0.5-1ppm of oxytetracycline or furacilin in the whole pool; Furazolidone is sprayed in the whole pool at 0. 1-0.2 ppm. The flocculent silk on the body surface of the water mold crab, especially on the wound, makes the sick crab move slowly, eat less, and the wound does not heal, which leads to the ulceration and spread of the wound tissue and leads to death. This disease is caused by the injury of river crab and the invasion of mold into the wound. ? Precautions: Don't hurt crabs during fishing, transportation and stocking. Add a lot of animal feed before molting. Treatment: malachite green 0.25PPM, 5 pieces in the whole pool, applied once after 5 days. Soak the sick crab in 3-5% salt solution for 5 minutes, and apply 5% phosphorus to the affected area. Ciliated protozoa can attach to the joints, feet, back shell, forehead, appendages and gills of ciliated crabs. There is more dirt on the body surface of the sick crab, and its activity and feeding ability are weakened. In severe cases, they will die before dawn. The disease is caused by excessive fertilization of pool water, long-term non-replacement, and excessive ciliate reproduction. ? Prevention method: change the pool water frequently to keep the water fresh. Treatment: spray 30% aldehyde 5- 10 ppm on the whole pond. Sprinkle 0.7PPM copper sulfate and ferrous sulfate (5:2) in the whole pool. Wash sick crabs with 0.5- 1ppm bromogeramine and 5- 10ppm potassium permanganate. Use 0.2-0.3 ppm malachite green to splash along the pond where the river crabs are densely populated, such as aquatic plants. The abdomen of the crab suffering from slave crab disease is slightly swollen. When the umbilical cover is opened, it can be seen that the milky white or translucent granular worms with a thickness of about 65438±0mm are parasitic on the accessory branches or chest plate. The diseased crab grows slowly and its gonads are stunted. The river crab seriously parasitized by slave crabs has a bad smell and cannot be eaten. The main causes of this disease are the high salt content in the pool water, the proliferation of slave crabs and the spread of infection by larvae. ? Preventive measures: thoroughly clean the pond and kill the crab slave larvae in the pond. Common drugs include bleaching powder, trichlorfon and formaldehyde. Mixed culture of a certain amount of carp in crab ponds can inhibit the number of crab slave larvae. In ponds with signs of disease, the development and spread of crab slaves can be suppressed by completely changing the pond water, injecting new water (salinity less than 1‰) or moving sick crabs infected with crab slaves to fresh water. Treatment? (1) soak the disease in 5PPM copper sulfate solution 10-20 minutes. Soak the sick crab 10-20 minutes with 20PPM potassium permanganate solution. Copper sulfate and ferrous sulfate (5∶2) were sprinkled all over the pond at the concentration of 0.7PPM. Cracks appeared at the junction between the head, chest and abdomen of the sick crab with incomplete molting, but the old shell could not fall off, and the sick crab turned black and finally died. The common diseases of raising crabs in ponds are related to the lack of some mineral elements in the growth process. Generally speaking, there are many parasites in the crab seedling stage. When there are many parasites, crab seedlings can't shed their skin and die. Young crabs and adults will also die if there are many parasites in their gills. Control method: soak the crab body with 10PPM malachite green for 45 minutes, or soak the crab body with IPPM bromogeramine solution until the tail falls off. Crabs will be clean.