There's trout. There's koura. There's the occasional catfish.

It seems there's the occasional goldfish too, as a Taupo man discovered when he came across a 30cm-long dead orange fish floating in the lake at Two Mile Bay last week.

Local real estate agent and keen fisherman Grant Bayley was out for a morning walk when he came across the expired fish on the lakeshore, and he immediately worried that it might be a koi carp, a destructive fish species which degrades waterways.

"I saw this fish floating on the edge of the lake and I'm a pretty keen angler and I thought it didn't look right so I went and got my net and scooped it out," says Grant.


Grant asked a friend passing by to take a picture, before taking the fish home to call DOC. In the meantime his friend made contact with local environmental advocate Dave 'Didymo Dave' Cade, and Grant soon received a call from DOC freshwater ranger Brenda Lawson, who came to inspect the fish. Although she thought it was likely to be a goldfish, she sent it to a DOC fishery scientist in Turangi, who confirmed she was correct.

No action would need to be taken, although if it had been a koi carp, an incursion response would be mounted because carp are a pest fish that "we really don't want" says Brenda.

The Conservation Department regularly receives reports of goldfish in the lake, she said.
They were first introduced in the late 1800s by a member of the Armed Constabulary and are found throughout Lake Taupo but prefer the shallower slow moving waters at Motuoapa and Waihi, as well as the warmer geothermal waters on the lakefront. Their number have been affected by catfish, which invade the same habitat. They are not thought to compete with trout.

As well as Lake Taupo, goldfish are also in lakes Hinemaiaia A and B, Lake Rotongaio south of Waitahanui, and possibly others.

The biggest goldfish Brenda has seen was about 30cm long. Colours can range from orange to bronze but the main difference from koi carp is in the teeth, she says.

"They [koi carp] can kill off waterways because they have these very grindy teeth. They can dig into the lake edges and chomp up all the mud and get all the goodness out of it and then discharge the sediment into the water, which makes it cloudy. You get deoxygenation and all the native plants die off and the lake becomes really unhealthy."

Koi carp have ravaged the lower Waikato River and breed prolifically that's why it's so important to check, clean and dry gear between waterways, to avoid transferring koi carp eggs, Brenda says.

She praised Grant for notifying the goldfish catch and Grant in turn says he's hearted by the quick response from DOC staff.

"Lake Taupo is considered one of the best wild freshwater fisheries in the world and for it to become contaminated by foreign fish species or plant matter would be a disaster."

The Ministry of Primary Industries has a 24-hour number to report water or land-based pests or diseases.

MPI Pests and Diseases Hotline: 0800 80 99 66 or the Waikato Regional Council on 0800 BIOSECURITY (0800 246 732) .