Control methods of five common diseases of crayfish

The method of "giving priority to prevention and combination of prevention and control" should be adopted to deal with the disease of crayfish. The following editor introduces several common diseases of crayfish and their control methods.

crawfish

1. Gill rot

Gill rot is caused by bacteria, characterized by black Gill filaments of crayfish and local mildew.

Prevention and control methods: the residual bait and dirt in the shrimp pond should be removed frequently and injected into new water, and the dissolved oxygen in the water body should be kept above 4 mg / L to avoid water pollution. The control method is to sprinkle the whole pool according to the proportion of 2 grams of bleach solution per cubic meter.

Black Gill disease

Black Gill disease is mainly caused by water pollution and Gill filament of crayfish is infected by mold. The symptom is that the gills of the crayfish change from red to brown or light brown until they become completely black, the gills atrophy, and the shrimp crouches on the shore and dies because of difficulty breathing.

Prevention and control methods: keep the water clean, sufficient dissolved oxygen, and regularly use quicklime to regulate water quality. The diseased shrimp is washed 2 times with 3%-5% salt water for 3-5 minutes each time, or sprinkled throughout the pool with 10 grams of methylene blue dissolved water per cubic meter.

Third, rotten tail disease

Rotten tail disease is caused by crayfish injury, cannibalism or infection by chitin-decomposing bacteria. In the early stage of infection, there are blisters in the tail of crayfish, and the edges are festering, necrotic or incomplete. With the deterioration of the disease, festering develops to the whole shrimp tail, and finally the whole tail falls due to fester.

Prevention and control methods: when transporting and releasing crayfish seedlings, do not pile up and damage crayfish. Feed enough and evenly in order to prevent crayfish from competing for food during the feeding period. The disease was sprinkled in the whole pool with the proportion of 1520 grams per cubic meter of tea meal extract, or 5 kilograms of quicklime per mu of dissolved water.

IV. Polycondensed disease

The pathogen is condensed worm, the symptom is that the crayfish is difficult to shell smoothly, resulting in death in the shelling process, larvae and adults can occur, and the harm to the young crayfish is more serious.

Prevention and control method: clear the pond thoroughly and kill the condensed worms in the pond. The culture pond where the disease occurs can often change a large amount of water and reduce the number of condensed worms in the culture pond.

5. Ciliosis

Trichoderma and bell worms are common pathogens of ciliosis. Ciliates are attached to the body surface, appendages and gills of crayfish. Excessive attachment will hinder the breathing, activity, feeding and shelling of crayfish and affect the growth of crayfish. Especially when a large amount of it is attached to the Gill, it affects the gas exchange of the Gill filament of crayfish, and finally leads to anoxia and asphyxiation.

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