Otago Fish & Game Central Otago is asking anglers to be on the lookout and report any sightings after a grass carp was caught recently in the lake.
Operations manager David Priest said it was suspected that the carp came from authorised releases into contained ponds.
It had possibly escaped during spring floods into Lake Hayes and swum down the Kawarau River into Lake Dunstan.
While it was unlikely the carp could breed, there was a risk of them spreading disease.
“The last thing we want is a disease entering highly valued fisheries,” Mr Priest said.
Grass carp, which commonly grow more than half a metre in length, are a herbivorous fish native to Asia used in parts of New Zealand to control aquatic weed growth.
They are artificially bred and grown on fish farms licensed by the Ministry for Primary Industries and their release is controlled.
MPI most recently authorised the release of 100 grass carp to artificial ornamental ponds near Queenstown in February 2023.
