A Waikato Regional Council project which aims to trap the pest fish, koi carp and recycle it into potting mix has received a financial boost.
The Waikato River Authority and Genesis Energy are to fund a $170,000 digester which dries and mulches the carp.
The fish are rich in phosphorus and nitrogen, making them ideal plant food.
The digester will be constructed alongside a large trap at Lake Waikare in July, to capture the fish which migrate up the Waikato River to the lake in spring.
Waikato Regional Council says koi carp compete with native species for food and stir up sediment which causes the growth of toxic algae.
Biosecurity spokesperson John Simmonssays the project will significantly reduce their numbers and breeding potential.
The potting mix will be distributed to those who are involved with the planting of native trees along the Waikato River and its tributaries.