A year-and-a-half after catfish were first discovered in Lake Rotoiti in the Bay of Plenty there's evidence to suggest the population is exploding.
If the pest species establishes a stronghold in the region, it could spell the end of the local trout fishing industry.
The discovery of just one baby catfish near Lake Rotoiti 20 years ago sent shockwaves through the fishing community.
Fast forward two decades and that nightmare has begun.
In March last year a single catfish was caught and a second was spotted during weed harvesting.
Since then, dozens more have been captured in the lake and more than 3200 in one particular bay.
"They are tough little critters and they can survive up to 24 hours out of water," says Donald Atkinson, Lake Water Quality Society chairman.
That means they're able to hitch a ride from one location to another.
"At the moment numbers are low, but if they establish a stronghold here they could ruin our trout fishery," Mr Atkinson says.
That's because they're carnivorous and feed on small native fish, as well as trout and their eggs.
Catfish are not native to New Zealand and were first discovered here in the late 1800s.
For many years the only known populations were in the lower Waikato River and in Lake Mahinapua, south of Hokitika. But in 1985 they were found in Lake Taupo, in '97 in Kaituna Lagoon near Lake Ellesmere and 2003 in a stream entering Hokianga Harbour.
"Unlike Lake Taupo where they're also established, Lake Taupo is very deep, but our lakes here have got very shallow embayments," says Mr Atkinson.
"We've got a contractor engaged. He's going around systematically netting, using live capture nets," says Shane Grayling, biosecurity team leader at Bay of Plenty Regional Council.
The Bay of Plenty Regional Council is working with international researchers to try to come up with innovative control mechanisms.
Boaties are also urged to take extra care and wipe down their vessels before and after use.