Chairman of Southland's Hokonui Runanga Rewi Anglem is worried about the long-term effect of a mysterious illness on the population of kanakana in the Mataura river.
Hundreds of the fish - a type of lamprey - have been found with red coloured fins and red contusions on their bodies.
The Southland Regional Council is warning people not to eat the fish and has sent samples to the Ministry of Agriculture and Forestry (MAF) for laboratory testing.
Mr Anglem says he contacted the Council about a fortnight ago after seeing strange looking kanakana in the Mataura.
He says he's been catching the fish for over 50 years and never seen anything like it before.
Mr Anglem says kanakana have been a valuable source of food for local Maori for hundreds of years.
