Aquaculture

Koi Herpesvirus and Fish Welfare

Koi herpesvirus (KHV) causes devastating mortality in carp and koi, with significant welfare implications and ecological consequences.

Key Facts

KHV causes mass mortality events with up to 95% lethality in outbreaks
The virus spreads through water, shared equipment, and infected fish
Clinical signs include gill necrosis, skin lesions, and lethargy
KHV is a notifiable disease in the UK and many other countries
Carp are the world's most farmed fish by number

Welfare Considerations

KHV causes severe respiratory distress as gill tissue is destroyed, making breathing progressively more difficult. Infected fish show signs of profound distress including surface gasping and loss of coordination before death. Mass mortality events cause widespread suffering before culling can be implemented. Survivors that harbour the virus can be triggered to shed it again by temperature stress.

What You Can Do

Never release pet fish into natural water bodies
Quarantine new fish for at least 14 days before introducing to ponds
Clean equipment thoroughly between different water bodies
Report suspected KHV outbreaks to the fish health authority
Support biosecurity research in carp aquaculture