Koi pox, also known as carp pox, is caused by the herpesvirus Cyprinid herpesvirus-1 (CyHV-1). This virus primarily affects common carp and koi, which are the same species, Cyprinus carpio.
While koi pox is related to koi herpesvirus (KHV), it's a separate virus with lower virulence and a different rate of transmission. It doesn't cause the same level of mortality as KHV.
Here's how the virus affects koi:
- The virus enters the fish through open wounds or mucous membranes.
- It replicates within the fish's cells, causing the characteristic white, gray, or yellow pox-like lesions to appear on the skin, fins, and gills.
- These lesions are typically raised and can be quite large.
- The disease can weaken the fish's immune system, making them more susceptible to other infections.
