PRATT – Following a series of small-to-large scale fish die-offs that occurred throughout Kansas in June – die-offs that appeared to only affect common carp – fisheries biologists with the Kansas Department of Wildlife, Parks and Tourism suspected Koi herpes virus as the culprit. KDWPT Fisheries biologists collected samples from Hillsdale Reservoir, Kansas’ hardest hit waterbody, and sent them to the Aquaculture and Fisheries Center at the University of Arkansas at Pine Bluff for testing. On July 24, test results arrived confirming the presence of Koi herpes virus. 

The first sightings of dead common carp were reported in mid to late May at Clinton, Hillsdale, and Pomona reservoirs. Die-offs continued through the month of June before fully ceasing in early July. Though the total number of common carp affected is unknown, KDWPT fisheries biologists estimate that number to be in excess of 5,000. 

“These die-off events largely occurred during the species’ spawning season, which is already a very stressful time for fish,” KDWPT aquatic nuisance species coordinator Chris Steffen said. “Add to that a cool spring quickly shifting to hot summer weather, and it’s likely these fish were more stressed than normal, making them more susceptible to disease.” 

Koi herpes virus is a DNA-based virus that stays with the infected fish for the duration of its life. Physical symptoms that can manifest in infected fish include patches of red, white or pale discoloration, bleeding gills, sunken eyes, or blistering. Koi herpes virus has no documented effect on humans.