A bacterial disease responsible for killing kanakana or lamprey in two Southland rivers has been found in a single trout in an isolated Otago hatchery.
Fish and Game in Southland says the disease had been detected in kanakana from the Mataura and Waikawa Rivers.
It says the outbreak may also be present in four other rivers.
Fish and Game says it has had to cancel the release of 200 trout and salmon into Te Anau Boat harbour this weekend.
An Invercargill-based senior officer, Zane Moss, says it would be irresponsible to release fish into other regions.
He says the disease outbreak serves as a timely reminder for all fishers to check, clean, and dry all their gear when moving from one fishing spot to another.