A biosecurity operation is under way after the discovery of catfish in Lake Rotorua.

Six of the pests have been caught, sparking fears for the environment.

Council biosecurity team leader Shane Grayling told Larry Williams they are opportunistic predators.

“They can impact ecosystems for a number of reasons.

"They will continue to consume just about anything they come into contact with. The main issues are predation of species of significance, and also competition for feeding space with other species."

Grayling says their feeding habits can also produce nutrients that affect the water quality.

He says that catfish likely spread from nearby Rotoiti, where they have been found since 2016, after hitching a ride on a boat trailer.

“There is the potential that someone has introduced it accidentally, and we also can’t discount the fact that people do sometimes introduce weird and wonderful species for certain reasons.”

He says systematic netting will be used to control the population, though they need new technology to help with their efforts.

Grayling says they know they can catch catfish, but there are doubts they can catch enough to control the population.

LISTEN TO SHANE GRAYLING TALK WITH LARRY WILLIAMS ABOVE