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Recent Outbreak of Koi Herpesvirus disease (KHV)

2 Jul 2019

An outbreak of Koi Herpesvirus (KHV) in koi carp from a private garden pond in the Midlands was recently confirmed through laboratory testing in the Marine Institute. KHV is a devastating disease of carp and is associated with high mortalities. In this particular case 60% of the koi carp present died. KHV is listed as a notifiable disease under EU regulations and the island of Ireland was declared free of the disease after a targeted two-year surveillance programme completed in in 2013. This is only the second outbreak of KHV ever recorded in Ireland. Fish that recover from a KHV infection are likely to be carriers of the disease therefore, in order to maintain Ireland’s disease-free status, all surviving koi carp present at the site were culled and the pond system was disinfected under the supervision of the Fish Health Unit (FHU) of the Marine Institute.

Clinical signs of KHV disease may include white or necrotic patches on the gills, sloughing mucous and sunken eyes. Disease usually occurs when water temperatures exceed 16˚C. Anyone noting carp mortalities associated with similar symptoms should immediately contact the Fish Health Unit at

Keepers of koi carp and other ornamental fish are reminded that they should only source fish from reputable retailers within the Republic of Ireland, or alternatively if you wish to bring fish in from outside of the state, you must first register with the Marine Institute. All imports of ornamental fish must come from establishments certified to be disease-free and each movement must be approved by the Marine Institute in advance. Full details of how to register and apply for movements are available here. These controls are critical to protect Ireland’s disease-free status.

If you require further information please contact the FHU at