The Department for Environment, Food and Rural Affairs (Defra) has announced significant changes to how Koi herpesvirus (KHV) outbreaks will be managed in recreational fisheries across England and Wales.
The updated policy, which takes effect from June 2026, reflects a shift toward a more targeted and evidence-based approach to aquatic animal health regulation.
Officials say the decision follows years of scientific research showing that KHV is now widespread in wild and recreational fish populations and that existing statutory controls have had little impact on limiting its spread.
Reporting KHV Remains a Legal Obligation
Despite the changes in disease management, fishery operators and stakeholders are still legally required to report any suspected or confirmed cases of KHV to the Fish Health Inspectorate (FHI).
Authorities stressed that the reporting requirement under the Aquatic Animal Health (England and Wales) Regulations 2009 remains fully in force.
Failure to notify the FHI of suspected disease outbreaks or unusual fish mortality continues to be a breach of the law.
New Response Framework for Suspected Outbreaks
Under the revised system, the Fish Health Inspectorate will continue to receive, assess, and monitor reports of suspected KHV cases.
However, when the affected fish species, environmental conditions, symptoms, and mortality patterns strongly indicate KHV—and there is no indication of another listed or emerging disease—the FHI will generally avoid routine statutory sampling and will no longer automatically impose disease control restrictions on recreational fisheries.
Instead, officials will focus on maintaining communication with fishery operators, monitoring developments, and offering practical biosecurity guidance aimed at reducing the impact of outbreaks.
Investigations Still Possible in Higher-Risk Situations
The agency emphasized that it retains the authority to intervene if circumstances change.
Should evidence emerge suggesting another serious disease threat, or if the risk profile of an outbreak increases, the FHI may launch a more detailed investigation.
Such actions could include tracing the origin and spread of the disease, collecting samples for laboratory analysis, and introducing disease control measures where deemed necessary.
Testing would be carried out through the relevant National Reference Laboratory at Cefas’ Weymouth facility.
Commercial Aquaculture Operations Remain Subject to Controls
While recreational fisheries will see a more flexible regulatory approach, stricter disease controls will continue to apply to authorized aquaculture production businesses and facilities involved in fish trading and movement.
Fish farms, importers, wholesalers, and KHV-approved compartments will remain under existing disease surveillance and control requirements because of their greater potential to spread infection through fish transfers.
Fishery managers may also choose to commission private diagnostic testing to assist with operational decision-making.
Environment Agency Continues Key Fisheries Role
The Environment Agency (EA) will maintain its responsibility for safeguarding freshwater fisheries in England.
During KHV outbreaks, the agency may work directly with fishery operators to provide advice on management practices and assess requests for activities such as fish movements.
Any decisions regarding these activities will be made on a case-by-case basis under the EA’s fisheries management powers.
Officials noted that these responsibilities are distinct from the Fish Health Inspectorate’s legal role in disease surveillance and control.
Scientific Evidence Behind the Policy Change
The revised strategy follows extensive reviews conducted by Cefas scientists and epidemiologists over more than 15 years of outbreak investigations and disease monitoring.
According to those assessments, KHV is now firmly established across recreational fisheries in England and Wales.
Researchers found that outbreaks are often triggered by environmental factors and stress, while effective fishery management and strong biosecurity practices can help reduce both the likelihood and severity of disease events.
The reviews also concluded that recreational fisheries generally pose a low risk of transmitting the virus elsewhere because they typically involve limited movement of live fish.
Existing Controls Found to Have Limited Impact
One of the key findings underpinning the policy change is that statutory controls have not been shown to significantly reduce either the frequency of KHV outbreaks or the overall spread of the virus.
Scientists also highlighted that KHV can persist in apparently healthy carp populations, with infected carrier fish often displaying no visible signs of illness.
Because the virus is already widespread and capable of remaining hidden within fish populations, routine regulatory controls at recreational fisheries were found to provide limited epidemiological benefit.
Focus Shifts to Risk-Based Disease Management
Defra says the new framework will allow regulatory resources to be concentrated where they can have the greatest impact on aquatic animal health.
The updated model prioritizes surveillance, monitoring, and practical support for fishery operators rather than automatic restrictions.
Officials believe this proportionate approach will maintain strong disease oversight while reducing unnecessary regulatory burdens on recreational fisheries.
The government has indicated that the policy will remain under review and may be adjusted in the future as new scientific evidence emerges.
How to Report a Suspected Case
Anyone who suspects a listed fish or shellfish disease, including KHV, must immediately notify the Fish Health Inspectorate at the Centre for Environment, Fisheries and Aquaculture Science (Cefas).
Reports can be made by telephone on 01305 206700, where a 24-hour emergency reporting service is available, or by email at fhi@cefas.gov.uk.
Authorities also require prompt reporting of any unusual increase in fish deaths, whether to the FHI directly or through a veterinarian.
Officials reiterated that reporting suspected disease outbreaks is a legal responsibility and remains a vital part of protecting aquatic animal health in England and Wales.
