Characteristics of disease in shrimp culture

The vitality and swimming ability of prawns are weakened.

Healthy and disease-free prawns usually live in the middle, lower layer or near the bottom of the culture water, which is not easy to see; sometimes some shrimp can be found on the embankment, but they are lively, swim fast and have strong bouncing ability.

Sick shrimp activity ability is weak, swimming is slow, in artificial stimulation, slow response, do not escape, some turn on the surface of the water or swim up and down aimlessly; some lie on the side of the pool in shallow water; some habits are abnormal, such as Penaeus japonicus does not dive sand during the day.

Food intake decreases or stops feeding, and growth is slow.

Healthy and disease-free shrimp groups can be seen to compete for food actively during feeding (bait). Half an hour later, samples were taken and checked. More than 80% of the prawns had full stomach and intestines. After continuous observation for 3 mi for 5 days, it could be seen that the shrimp grew well and the shrimp body was strong. On the other hand, under routine feeding, sampling observation after half an hour showed that more than 50% of the shrimp had an empty stomach and residual bait appeared in the pond; non-acute diseases were observed continuously for 6 days, the shrimp did not grow, became thinner and thinner, and the residual bait also increased significantly.

Abnormal body color and Gill

Healthy and disease-free shrimp, the body is transparent or translucent, especially larvae and minors, the body color is normal, bright, no dirt, algae, protozoa and other attachment; through both sides of the head and chest, the gills are clean and clearly visible. The body color of diseased prawns is gray, the pigment spots on the surface of carapace increase, some appear white spots, brown spots, carapace ulcers; the appendages are incomplete, the tentacles are broken, some appendages turn red, the muscles are white and turbid, and the shrimp body spasms show cramps; Gill blackening, some yellow or white gills, dirt attached to the gills or fixed protozoa, algae and so on.

The mortality rate is rising.

Under normal circumstances, the mortality rate of a shrimp culture pond within 5 days should be close to zero; within half a month or 10 days of its culture and production, individual shrimp bodies died, and their population activity, feeding, body color, gills and other phenomena were not abnormal, which can be regarded as natural reduction, but if more than 0.1% mortality occurs in the shrimp pond within 2 days, it may be the initial stage of the disease and should be carefully observed and examined carefully.