2024 Volume 59 Issue 1 Pages 9-16
The susceptibility of larvae and juvenile koi carp (0–56 days post hatch; dph) against carp edema virus (CEV) was investigated by experimental infection with the immersion method using homogenized suspension from gill tissues of the diseased fish. Although no CEV mortality was occurred during the larval stage (0–7 dph), CEV-positive fish were found at all dph (positive rate 12–48%). In the juvenile stage (14–56 dph), the positive rate and mortality increased with dph. The positive rates and mortality were positively correlated with the total length of fish. The positive rates of the fish that were greater than 20 mm in total length exceeded 50% and the dead fish caused by CEV-infection were observed at 30 mm in total length or greater. These results indicate that the CEV susceptibility of larvae and juvenile koi carp increase with fish size rather than dph.
