Fish can be noxious too

On the 12th October 1980, nine species of fish were declared noxious pests, in Amendment 16 of the Freshwater Fisheries Regulations 1951. The fish are a variety of scoundrels: the Walking Catfish, European Carp (including Japanese Koi Carp), Pike, Rudd, three species of Piranha, and two species of Tilapia.

Piranha? In New Zealand waters?

Relax. The piranhas are held only at the Napier Aquarium Display and are permanently on exhibition there. Pike and European Carp are not known in New Zealand waters—there are none anywhere in the country, as far as can be discerned. For the past five years or so Koi Carp have been sold as aquarium fish by pet shops. They are known to be present in both Islands, mainly as a garden pond inhabitant, but many farm dam populations do exist. Tilapia species likewise have been sold by pet shops as a tropical fish and exist in home aquaria. Walking fish are presently believed to be held by some private fish fanciers. The Catfish especially can be seen as motivating the change in the Regulations. It is a predatory fish, which if it escaped, could move overland and become a serious threat to our freshwater fishing industry.

Rudd, of course, are widely acclimatised from Hamilton northwards. Any rudd or escaped piranhas or Walking Catfish taken by anglers must be immediately killed. A fine (not exceeding one thousand dollars) may be imposed on persons convicted under the noxious fish Regulation.