Matters needing attention in crayfish culture in winter due to slow growth and poor disease resistance

As the weather turned cold, the crayfish began to live in caves for the winter. The growth is slow in this period. It is necessary to strengthen the management of crayfish and improve the survival rate and economic benefits of crayfish in overwintering season.

Crayfish feeding

The choice of overwintering pool: an area of 3 Mu and a slope ratio of 1 to 2.5 mu. Leeward to the sun, sufficient water, no pollution, water depth of more than 1.5 meters. Before putting the crayfish, drain the pool water and disinfect it thoroughly with quicklime. 7-10 days before shrimp release, water injection and fertilization were applied with 100-150kg per mu of rotten animal manure to cultivate plankton.

Transplant aquatic plants: transplant aquatic plants such as water hyacinth, water peanut, Malay and other aquatic plants, with a coverage rate of more than 40% and a uniform layout. Aquatic plants can absorb excess fertilizer in the pool and prevent anoxia through photosynthesis. At the same time, aquatic plants can grow into aquatic insects that supplement crayfish animal protein.

Daily management: (1) timely feeding. Before overwintering, feed more animals to strengthen the physique and improve the survival rate in winter. During the overwintering period, the lobster does not look for food, but when the weather is sunny and warm, the lobster leaves the cave and forages a small amount of food, which can be fed to small fish and shrimp, mussel meat, animal viscera and so on to replenish the body nutrition. (2) improve the water quality. During the overwintering period, the water level in the pool is kept above 1.5 meters to maintain the water temperature of the pool. If the water level is too shallow, it is necessary to replenish the water at the right time to prevent the lobster from freezing to death; if the water quality is too fertilizer, change the water at the right time, keep the dissolved oxygen in the water above 4kg/ liter and the transparency above 40cm, and prevent the crayfish from asphyxiation due to lack of oxygen. (3) patrolling the pool regularly. Patrol the pool twice a day, find abnormalities and take countermeasures in time. During the overwintering period, 20 kg of quicklime will be sprinkled every 10 seconds for 15 days to disinfect the water body, replenish calcium and prevent diseases.

Prevention of crayfish frost injury: crayfish is a variable temperature animal, when the water temperature is lower than 4 ℃, it will be frostbitten or frozen to death. When the crayfish frostbite, the abdominal muscle appears white spot, with the aggravation of the disease, the white spot becomes larger, extending to the whole body. At the beginning of the disease, crayfish lie flat in shallow grass; in severe cases, symptoms such as paralysis and rigor appear. Do a good job in preventing cold and freezing, especially in early winter, when the natural water temperature drops to 10 ℃, the pool water should be put in place. In autumn and winter, feed fatty feed, such as bean cake and peanut cake, to increase the disease resistance of crayfish. During the overwintering period, organic fertilizer or straw can be fed to increase the water temperature. In the later stage of shrimp stocking, fish rattan essence can be used to remove fish that harm crayfish and build a protective net.