Fish & Game is concerned at the discovery of a bacterial fish disease in a trout in Otago and fears it could spread further.
The Ministry of Agriculture has confirmed that a single juvenile trout in a Fish & Game hatchery on the Taieri River in Otago has tested positive for the same disease that is killing native lamprey or kanakana in Southland.
MAF says it's the first case to be found in trout but the bacterium can infect a range of fish including eels, salmon, whitebait and kokopu.
Otago Fish & Game Council chief executive Niall Watson says no other trout in the hatchery have shown signs of the disease so far.
But he thinks it is likely that the disease is going to spread through southern waterways since the native lamprey in the Mataura River - where the disease was first picked up - will be migrating into other lowland rivers that are open to the sea in the South Island and elsewhere.
"I would imagine that the disease is going to be widespread in the south of the South Island anyway but we don't know the implications of it at this stage and we're waiting for more advice from MAF."