What does it look like?
Rudd were illegally imported into New Zealand in 1967, and widely released into freshwater systems. Rudd are darker on their backs than on their bellies and have bronze highlights when the light catches their scales. Their fins are usually bright reddish-orange. They do not have any barbels around their mouth, a feature that tells them apart from koi carp. They do not have spines on the front edge of the dorsal fin, but have projections at the bases of their pectoral and pelvis fins. Rudd are usually 200-250mm long. Juveniles eat plankton and midges. Adults are mainly herbivorous but also consume invertebrates and occasionally small fish.
Freshwater, including lakes, ponds, rivers and streams. They also tolerate periods of exposure to brackish water.
Why is it a problem?
Juvenile rudd are carnivorous, but as adults their diet consists mainly of aquatic plants. A high-density rudd population could impact on native fish and plant communities, particularly where plant communities are limited. Rudd are prolific breeders and are known to be invasive overseas. They may be advantaged by release from native-range parasites.
High fecundity. Sexually mature at around one year old for male, and around two years old for females. Spawn in spring-summer, producing around 1000-100,000 eggs.
Please contact the Northland Regional Council for more information if you think you have seen this pest.