Cyprinid herpesvirus 3 (also CyHV-3, koi herpes virus or KHV) is a species of virus causing a viral disease that is very contagious to the common carp Cyprinus carpio. KHV has never been associated with disease in any other species.



First detected between 1996 and 1998, KHV caused a mass mortality of common carp following initial outbreaks in the United Kingdom, Germany, and Isreal. 33 countries around the world how now detected KHV, including the United States. In the environment of intensive aquaculture, Koi Herpes Virus is thought to have originated from a benign common carp virus that increased in virulence



KHV is a DNA-based virus. After discovery, it was identified as a strain of herpesvirus. Like other strains, KHV stays with the infected fish for the duration of their lives, making the recovered and exposed fish potential carriers of the virus. Koi fish infected with KHV may die within the first 24–48 hours of exposure. It is most commonly found in ornamental koi, which are often used in outdoor ponds or as feeder stock. Changes in the specimen’s behaviour may also indicate the presence of KHV. Behavioural symptoms may include disorientation, hyperactivity and potentially isolation, in which the specimen detaches themselves from the shoal.



Gill mottling

Red and white patches appearing on gills

Bleeding gills

Sunken eyes

Pale patches



If you have concerns about KHV please contact us at (805) 341-3474.