There are some 40 species of freshwater fish in New Zealand, 10 of which have been introduced from other countries.
The native species are contained in 11 families. They are believed to have evolved from marine ancestors during New Zealand's geological history; in fact, most of the families still have species which inhabit or can tolerate salt water at some stage of their life cycle. There is one species of lamprey (Geotridae), Geotria australis, which also occurs in Australia and South America. The eels (Anguillidae) are represented by two species, the long-finned eel, Anguilla dieffenbachii, and the short-finned eel, A. australis schmidtii. The family Galaxiidae contains the most species (c. 18); there is no common name for this group apart from “the galaxias”, which is preferable to the ambiguous term “native trout” often applied. Many of the Galaxias species are rare and known only by specialists. The commoner ones include Galaxias attenuatus, the inanga, whitebait, or “minnow”. Galaxias fasciatus, the kokopu or banded galaxias, is found throughout the country. Galaxias alepidotus, the giant kokopu, is the largest native freshwater fish (except for the eels), reaching a length of at least 17 in. (larger specimens being recorded in early times). It is dark brown in colour, strikingly marked with golden spots and crescents. Three members of the family are known as “mudfish”, having the remarkable ability to remain dormant for long periods of time buried in mud. Normally they live in swampy or muddy water, Galaxias burrowsius in Canterbury, Neochanna apoda in the South Island and lower North Island, Neochanna diversus near Auckland. The smelt family (Retropinnidae) contains four species of the genus Retropinna (called paraki by the Maori). They are small fish, 2–6 in. in length, pale green or grey in colour with bright silver sides. Young smelt frequently ascend rivers in company with whitebait. The grayling, Prototroctes oxyrhynchus (family Prototroctidae), is New Zealand's mystery fish. Although extremely abundant at the end of last century it has now virtually disappeared. It is no relative of the European or American grayling, being given that name in error by early settlers, and is better called by its Maori name of upokororo. A related species occurs in Australia. The torrent fish or shark bully, Cheimarrichthys fosteri (papanoko of the Maori), is the only known species of its family (Cheimarrichthydae). About 4 in. in length, coloured light grey with dark diagonal markings it frequents rapids and fast-flowing streams, after spending its larval life in or near the sea. The bullies or gobies (Gobiomorphidae) make up the last group of native fish. Six species are contained in the two general Gobiomorphus and Philypnodon. The better known of these are G. basalis, the common “cockabully”; G. radiata, the redfin bully; G. gobioides, the giant bully (reaching 9 in. in length); and P. hubbsii, the bluegill bully. Normally regarded as only a drab grey, many of the bullies have quite attractive colour patterns. Most are 3–5 in. in length. Bullies are widely distributed throughout New Zealand.
by Brian Turnbull Cunningham, B.SC., Senior Fishery Officer, Marine Department, Wellington.
- Native and Introduced Freshwater Fish, Woods, C. S. (1963).