Cyprinus carpio Koi carp are an ornamental strain of the common carp native to Asia and Europe. They were introduced to New Zealand accidentally in the 1960’s as part of a goldfish consignment. They contribute to water quality deterioration and are a serious problem in Australia, as well as New Zealand.
Description and Life History:
Koi carp resemble goldfish except that they have two pairs of barbels (feelers) at the corners of their mouth. They are highly variable in colour, often with irregular blotching of black, red, gold, orange or pearly white. Koi carp are long-lived fish and grow to about 750 mm in length.
What damage do they do?
The way that Koi carp feed stirs up the bottom of ponds, lakes, rivers muddying the water and destroying native plant and fish habitat. Koi carp are opportunistic feeder, eating insects, spawn, juvenile fish of other species and diverse range of plants and organic matter. They feed like a vacuum cleaner, sucking up everything and blowing out what isn’t wanted. Aquatic plants are dislodged in the process and unable to re-establish. Koi carp cause habitat loss for plants, native fish and waterfowl.
Where are they found in NZ?
Koi carp prefer still waters in lakes, or backwaters in rivers. They are very tolerant of poor water quality, contributing to water quality decline.
Koi carp are widespread in Auckland and Waikato. They are spreading into Northland and they have been found in isolated places in Wanganui, Hawkes Bay and Wellington. Koi carp are not thought to be in the South Island.
To help stop their spread a containment area between Auckland and Hamilton was created. In the containment area, recreational fishing is permitted, but all Koi must be killed when caught. Koi carp outside of the containment area are considered a serious incursion and control options will be investigated.