The Cyprinidae family is one of the largest of the freshwater fish families with about 1450 known species. None are native to New Zealand, but several species have been introduced here. Generally carp have large scales, small barbels around their mouth, and no adipose fin. There are many exceptions to this, however, as might be expected in such a large family. The carp species present in New Zealand are:
Carassius auratus (goldfish)
Ctenopharygnodon idella (grass carp)
Cyprinus carpio (koi carp)
Hypophthalmichthys molitrix (silver carp)
Leuciscus idus (orfe)
Scardinius erythrophthalmus (rudd)
Tinca tinca (tench)
Cyprinids have been cultured as a food fish for thousands of years in their native countries. No such industry exists in New Zealand, although two of the species listed above, grass and silver carp, were brought here as potential aquatic plant or algal control agents. Neither of these species has established feral stocks here, but the other carp species have, although the precise status of orfe is uncertain. With the exception of goldfish, rudd and tench, the carps are confined to the North Island in New Zealand. None have spread to Chatham or Stewart Island.
Most of the carp species in New Zealand have no teeth and so as adults they feed mainly on plants and algae. However, juvenile fish will eat small animals such as snails. Spawning occurs during summer and carp prefer aquatic vegetation as an egg laying substrate. Because of their feeding and spawning requirements, carps tend to be found in warm, weedy waters in lakes and slow-flowing rivers.