What are the characteristic signs of disease in shrimp farming

Reduced vitality and swimming ability in shrimp

Healthy, disease-free shrimp usually inhabit the middle and lower layers of the farming water body or near the bottom, and are generally not easy to see; sometimes some groups of shrimp can be found on the pond banks, but they are lively in movement, swim quickly, and have strong jumping ability.

Sick shrimp have weak activity ability and swim slowly; when stimulated by humans, they respond sluggishly and do not flee; some spin in circles on the water surface or swim up and down without direction; some lie prostrate or on their sides in the shallow water at the pond edge; some show abnormal habits, such as Japanese shrimp (Marsupenaeus japonicus) not burrowing into sand during the day.

Decreased or stopped feeding, slow growth

Healthy, disease-free shrimp groups can be seen actively competing for food at feeding time; after half an hour, sampling inspection shows that more than 80% of the shrimp have full stomachs and intestines; continuous observation for 3-5 days shows good growth and robust shrimp bodies. In contrast, for sick shrimp under conventional feeding, sampling observation after half an hour shows that more than 50% of the shrimp have empty stomachs, and leftover feed appears in the pond; in non-acute disease cases, continuous observation for 5-6 days shows no growth of the shrimp, progressive emaciation, and a marked increase in leftover feed.

Abnormal body color and gills

Healthy, disease-free shrimp have transparent or semi-transparent bodies, especially juveniles and immature shrimp; their body color is normal and vivid, with no dirt, algae, protozoa, or other attachments on the body surface; through the head-thorax carapace on both sides, the gills are clean and clearly visible. Diseased shrimp have dull gray body color, increased pigment spots on the carapace surface, and in some cases white spots, brown spots, and carapace ulcers; incomplete appendages, broken antennae, and in some cases reddened appendages, white turbid muscles, and shrimp bodies with spasms appearing as cramping shrimp; gills turn black, and in some cases yellow gills or white gills, with dirt or attached protozoa, algae, and the like on the gills.

Increased mortality

Under normal circumstances, the mortality rate in a farmed shrimp pond should approach zero within 3-5 days; during the farming production process, if individual shrimp die within half a month or 10 days, and the group's activity, feeding, body color, gills, and so on show no abnormal phenomena, it can be regarded as natural reduction; however, if a mortality rate of more than 0.1% occurs in the shrimp pond within 1-2 days, it may be the initial stage of disease, and careful observation and detailed inspection should be carried out.