Prevention and control of diseases of cultured crayfish

As crayfish culture has just started, and the incidence of crayfish is less under rough culture conditions, the time for studying crayfish diseases is relatively short, so many problems have not been fully understood, especially viral diseases can not be effectively treated so far. The treatment of shrimp disease should be based on the policy of "giving priority to prevention and combining prevention with prevention". The following introduces several prevention and control methods of common diseases of crayfish.

1. Gill rot

The pathogen of Gill rot disease is bacteria, and the symptom is that the Gill filaments of diseased shrimp are black and mildew locally.

Prevention and control methods: often remove the residual bait and dirt in the shrimp pond and inject new water to keep the dissolved oxygen in the water above 4 mg / L to avoid water pollution. With bleach 2g / m3 dissolved water sprinkled in the whole pool, can play a better therapeutic effect.

Black Gill disease

Black Gill disease is mainly caused by serious water pollution and fungal infection of shrimp Gill. The symptom is that the gills change from red to brown or light brown, until they turn black completely, and the gills atrophy. The diseased shrimp often lie motionless on the shore, and finally die because of difficulty in breathing.

Prevention and control methods: keep the water clean, sufficient dissolved oxygen, and regulate the water quality with quicklime regularly. The diseased shrimp was washed 2 times with 3%-5% salt water for 3-5 minutes each time, or sprinkled with methylene blue 10 g / m3 dissolved water throughout the pool.

Third, rotten tail disease

Rotten tail disease is caused by injury of crayfish, cannibalism or infection by chitin-decomposing bacteria. At the initial stage of infection, there are blisters in the tail of diseased shrimp, edge fester, necrosis or incomplete. With the deterioration of the disease, ulceration develops from the edge to the middle. When seriously infected, the whole tail of diseased shrimp fester and fall.

Prevention and control methods: do not pile up and damage the shrimp body when transporting and putting in the shrimp seedlings. Feed should be fed fully and evenly during the feeding period to prevent shrimps from competing for food or killing each other due to lack of feed. When this disease occurs, sprinkle it in the whole pool with tea meal 15g / m3, or with quicklime 5kg / mu dissolved water.

IV. Polycondensed disease

The pathogen of Polycondensation disease is Polycondensation worm, the symptom is that it is difficult for shrimp to shell smoothly, diseased shrimp often die in the process of shelling, larvae and adults can occur, which do serious harm to young shrimp.

Prevention and treatment: clear the pond thoroughly and kill the pathogens in the pond. The occurrence of this disease can often change a large number of water and reduce the number of Polycondensates in the pool water.

5. Ciliosis

The common diseases of ciliosis include trichoderma, bell worm and so on. Ciliates are attached to the body surface, appendages and gills of adult shrimp and shrimp seedlings, which will hinder the respiration, activity, feeding and shelling of shrimp and affect the growth of shrimp. Especially when a large number of gills are attached, it affects the gas exchange of Gill filaments, which will cause anoxia and suffocation of shrimp.

Prevention and control methods: maintain a reasonable stocking density, pay attention to the environmental hygiene of shrimp ponds, often change fresh water, and keep the water quality fresh. Wash the diseased shrimp with 3%-5% salt water for 3-5 days, or with 25-30 mg / L formalin solution for 4-6 hours for 2-3 times.