"It's just really disheartening knowing that an introduced species to our country is yet again destroying our native species," says Mariana Te Rangi, DOC Senior Ranger.
They've been called many things and most of them aren't pleasant - underwater possum, river rat and gnarly pest. But the catfish epidemic that's plaguing lakes Rotorua and Rotoiti is no joke.
"The catfish to me would be like a taniwha," said volunteer, Davina Thompson. "There's good taniwha and bad taniwha, so this would be a bad taniwha."
William Anaru is the community co-ordinator working with the Te Arawa Lakes Trust to help "make our lakes great again". He's also in charge of the volunteer response to the catfish problem.
"Catfish are originally from North America. They've been here since the 1870s and there's a couple of theories there too; that they were released by the Acclimatisation Society into the Waikato River for a food source or they were brought over here on boats. Sailors brought them over because they could eat them as they came down and they just released them when they got here."
First recorded in Lake Rotoiti in 2016, catfish have become a major headache for the Department of Conservation.
"For the department it is a real concern," Te Rangi said. "Purely because of again, endangered species that could potentially become extinct due to an introduced pest."
Anaru agrees they are a pest in our waterways.
"Firstly because they're not native from here and secondly they're eating all the native fish, all the native crustaceans and they're a big threat to kōura, freshwater crayfish."
Catching catfish has become so important in this region, it was even included in the recent Te Arawa Games. An event that pitted 10 Te Arawa marae against each other in a variety of sporting events.
"Catfish killing was part of the kaitiakitanga stream of the Te Arawa Games," Thompson said.
"It was a first and actually ended up being our kids' best part of the event. They enjoy it because they've never seen catfish before. They've seen them on YouTube so for them to actually be part of this kaupapa and actually catch catfish and also learn about the things living inside the lake, is good for them."
To help minimise the spread of catfish, DOC has created the 'Clean, Check and Dry' concept.
"Clean down your boat, clean down your trailer. check every part of your boat, especially in your trailer because that's where catfish love to hide away, and let it dry for at least one minute," Te Rangi said. "
You do that before leaving the lake so that any debris or algae you may have, you leave it at that water port where ever you disembark."
The council estimates around 65,000 catfish have so far been caught between the two lakes, which begs the question… how many more to go?
"Probably another 100,000 maybe. We'll see," said Anaru.