Pathogenicity of a virus isolated from ascitic fluids of diseased Hirame was studied. Twenty Hirames, average body weight 180g, were injected with 10³ TCID₅₀/fish of culture grown virus intraperitoneally and then each 10 fishes were held at 10°C or 15°C. Five Hirames were injectedwith 0.1 ml of 10⁶ TICD₅₀/ml intramusculally and were held at 10°C using 100l aquariums.
During the 21 days post injection, 20%mortality were observed at 10°CIP and IM groups respectively but no mortality was observed at 15°C group and 10%FBS added MEM injected control groups. The virus titer of kidney tissues of died fish were 10^6.8-7.6 TCID₅₀/g.