Carp Pox in Fish

By PetMD Editorial on Jul. 2, 2008

Carp pox is a viral disease which is caused by the herpesvirus infection. It is one of the oldest diseases seen in fish. As the disease weakens the fish with infection and lesions, it leaves the fish susceptible to secondary infections by other microorganisms. The fish also become disfigured by the disease.

This disease usually affects carp and koi, but can also infect other types of fishes, and is therefore also named fish pox.

Symptoms and Types

Initially, the Carp pox shows up as milky skin lesions, which are smooth and raised in appearance. These lesions are not aesthetically pleasing and devalue the koi fish, which is known for its looks. In severe cases, the viral infection also diminishes the fish's immunity and leaves the lesion-filled (papillomas) area prone to a secondary infection by bacteria.


The Carp pox is caused by the virus herpesvirus-1 or HPV-1, which affects the fish's skin.


There is no treatment for carp pox infection. And while it may make the fish look more pleasant, the surgical removal of the lesions will not cure it of the virus.


The only way to prevent the viral infection from spreading is to destroy the infected fish and its environment.

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