Koi & Pond
Koi Herpes Virus (KHV)
Notifiable viral disease devastating koi populations worldwide. Mortality 80–100%. No cure — only management and prevention.
Severity: Critical
Koi Herpes Virus (Cyprinid Herpesvirus 3) is a notifiable disease in most jurisdictions. It causes sudden mass mortality at water temperatures of 22–28 °C (72–82 °F). Survivors become lifelong carriers.
Causes
Introduction of infected fish. Latent carriers can shed virus when stressed. The virus is shed in mucus, feces, and dead-fish tissue.
Treatment
There is **no cure**. Affected ponds must be quarantined; surviving fish are carriers and should never be sold or moved. Some hobbyists use "thermal therapy" — heating the pond to 30 °C — but this only suppresses the disease, not eliminates it.
Prevention
Buy only from KHV-tested suppliers. Quarantine new koi at 22–28 °C for 30 days — virus expresses within that window if present. Disinfect nets and equipment between ponds.
Frequently asked questions
Can KHV-surviving koi be safely kept?
Only in a completely isolated system that never mixes with other koi. Survivors shed virus whenever stressed and will infect any new fish introduced.
Is KHV dangerous to humans or other species?
No. KHV only affects common carp and koi (*Cyprinus carpio*). It is harmless to people, other fish species, and other animals.
Related conditions
Koi & Pond
Koi Herpes Virus (KHV)
Notifiable viral disease devastating koi populations worldwide. Mortality 80–100%. No cure — only management and prevention.
Critical
Koi & Pond
Koi Herpes Virus (KHV)
Notifiable viral disease devastating koi populations worldwide. Mortality 80–100%. No cure — only management and prevention.
Critical
Koi & Pond
Koi Herpes Virus (KHV)
Notifiable viral disease devastating koi populations worldwide. Mortality 80–100%. No cure — only management and prevention.
Critical