koi carpKoi carp

Common name: Koi carp
Botanical name: Cyprinus carpio
Management programme: Exclusion and Eradication

Where are they originally from?

Koi carp originate from China where they have been domesticated for several thousand years, but in New Zealand they are sometimes known as the ‘rats of the rivers’. In Lake Waikare in the Waikato, the Regional Council removed over 35 tonnes of carp over a four-year period.

Why are they a pest?

  • When Koi carp feed, they stir up the bottom of ponds, lakes, and rivers, muddying the water and destroying native plant and fish habitats.
  • They eat a wide range of food, including insects, fish eggs, juvenile fish of other species, and a diverse range of plants and other organic matter.
  • They feed like a vacuum cleaner, sucking up everything and blowing out what is not wanted. Aquatic plants are dislodged in the process and are unlikely to re-establish.
  • They are highly tolerant of poor water quality and contribute to water quality decline.

Where are they found?

  • They were detected in the Waikato River in 1983 at which time they were already well established.
  • Koi carp prefer warm enclosed waters or slow flowing rivers and canals.
  • In New Zealand koi carp are mostly found in the Auckland and Waikato regions, although they are occasionally found in fishponds on private properties at other locations throughout New Zealand.
  • Koi carp are present in selected locations in western Bay of Plenty.

What do they look like?

  • There are three major strains of Koi carp – the European, Chinese, and Japanese, all of which can be easily crossed and are very fertile.
  • Koi carp look very similar to a goldfish except that they grow to larger sizes (up to 10kg and 75cm long) and have two pairs of barbels at the corner of their mouths.
  • They are highly variable in colour, often accompanied with irregular blotching of black, red, gold, orange or pearly white.

What are the rules?


Koi carp is an exclusion pest. This means that it is not yet established in this area of the Bay of Plenty region. Bay of Plenty Regional Council is responsible for managing new incursions into the region.


Eradication pests are present in this area of the Bay of Plenty region but are limited in their size or extent of infestation. The eradication of these organisms is a feasible and cost-effective solution.  The Bay of Plenty Regional Council is responsible for their control or eradication from the region. Action may be required from landowners or occupiers to support a control operation.

How do you get rid of them?

As Koi carp are an Eradication and Exclusion species this means that it is the Bay of Plenty Regional Council's responsibility to control them. If you would like advice or think you have found koi carp, please contact the Bay of Plenty Regional Council and we will come to control it for you.

Management programme map