Prevention and Treatment Methods for Iridoviral Fish Disease in Pufferfish

Iridoviral fish disease affects many fish during the high water temperature period in the farming of pufferfish juveniles and adults. Through observation of the iridovirus in diseased fish using Giemsa staining, iridoviral fish disease occurs concurrently with botulism and vibriosis, and is a viral disease caused by infection with bacterial and parasitic fish diseases.

[Symptoms of iridoviral fish disease] The body color of the pufferfish darkens to brown. On visual observation, fish are commonly seen swimming slowly at the water surface or floating vertically in a weak manner; the body surface and fins of the pufferfish show hemorrhaging, resembling abrasions, and most diseased fish have cloudy eyeballs. Dissection of diseased pufferfish reveals an enlarged, black spleen, which sometimes also fades to pink. When pathological sections of the spleen are observed with Giemsa staining, most of the spleen cells are seen to be enlarged and spherical.

[Prevention and treatment methods for iridoviral fish disease]. There is currently no specific drug treatment for iridoviral fish disease, so prevention is the main approach. First, management of the rearing of pufferfish seedlings should be strengthened, and the rearing water environment of the pufferfish farm should be well controlled. Second, carry out low-density farming; the water temperature at the peak of the disease is 22E-23°C. Once the fish body is afflicted with monogenean skin parasitic diseases, parasites should be expelled promptly or the net cages replaced, and the farmed pufferfish moved to sea areas with a temperature above 24°C for farming. Third, when the water temperature is above 24°C, the feeding amount should be relatively reduced, and appropriate amounts of nutrients such as vitamin C and immune liver-strengthening agents should be fed to improve the disease resistance of the fish. Fourth, during the disease stage of the pufferfish, stopping bait feeding is effective in reducing the mortality of diseased fish, but various antibiotic drugs should also be cautiously trial-fed according to the situation, striving to achieve the goal of treating the disease.