Aquaculture

Koi Herpesvirus Welfare: Disease Impact on Carp and Koi

Welfare analysis of koi herpesvirus (KHV) -- a devastating disease of common carp and koi with major welfare implications.

Key Facts

Koi herpesvirus (KHV) is a highly contagious disease causing mass mortality in common carp and koi
It is a notifiable disease in the UK -- outbreaks require reporting to CEFAS
Affected fish show gill necrosis, sunken eyes, skin lesions, and respiratory distress before death
Mortality rates can reach 80-100% in susceptible populations within days
KHV is spread through water, infected fish, and contaminated equipment
There is no licensed treatment -- management relies on biosecurity and preventing introduction
The welfare impact is severe -- affected fish suffer respiratory distress and rapid deterioration
Ornamental koi keepers should never release fish into natural waterways

Welfare Significance

KHV causes rapid, severe welfare deterioration in affected fish populations. The respiratory distress and rapid systemic collapse mean individual fish experience acute suffering. Prevention through strict biosecurity is the only effective welfare protection -- once KHV enters a population, welfare harm is inevitable. Responsible fishkeeping including quarantine and no-release policies protects both fish welfare and wild carp populations.

What You Can Do

Quarantine all new koi and carp for at least 6 weeks before introducing to established ponds
Never release pond fish into natural waterways -- it risks introducing KHV to wild carp populations
Report suspected KHV to CEFAS immediately -- early reporting limits outbreak spread
Source fish from reputable suppliers with disease health assurance