:: Inanga Fish, New Zealand Fresh water fish ::


The inanga is well known to New Zealanders as one of five native freshwater fish species whose juveniles (young) make the whitebait run, swimming upstream from the sea to spend their adult lives in rivers. Inanga make up about 95% of the total whitebait catch. The adult grows to around 10 centimetres long and can be easily distinguished from the adults of other fish found as juveniles in the whitebait run by its silver belly and forked tail.

Galaxias, the name given to species of the Galaxiidae family, is attributed to their profusely spotted coloration which resembled the Milky Way galaxy (McDowall, 2000). Each of the species of Galaxias has distinctive features and coloration. Inanga (Galaxis maculates) has a greenish translucent band along the middle of the sides which has resulted in a certain variety of greenstone being named after it by the Maori (McDowall, 1990). The eyes, gill covers and belly are bright and silvery in coloration but the whitebait (juveniles) are translucent. The body is small, sleek and slender, with a small head and large eyes (McDowall, 2000).

You can find inanga throughout New Zealand and its offshore islands, and in South America and Australia. They live in open rivers, streams, lakes and wetlands and can often be seen shoaling in open water, especially at breeding time. We’ve found inanga in larger rivers like the Ruamahanga, Pahaoa, Hutt, Otaki and Waikanae. They are poor climbers, which is why they don’t travel too far inland unless the river has a gradual slope.


The greatest distance inland we’ve found them is in the lower Mangatarere Stream in the Ruamahanga River catchment. They’re also found in our smaller rivers and streams, like the Waitohu, Wharemauku, Pauatahanui, Makara, Pounui and Putangarua.

Inanga has a similar life cycle to other whitebait species, which is described in the information sheet Can fish fly? that is part of this series. However, we know more about its breeding habitats than other native freshwater fish because we see it more often.

In late summer and autumn inanga swim downstream to estuaries, where they spawn (lay eggs) during high tides and high river flows. They prefer areas in the upper parts of the estuaries, and can be seen squirming onto the wet river banks where they lay their eggs among the riverside vegetation. You can sometimes tell inanga are spawning by the milky colour in the water near the river bank.

We have identified where inanga spawn in 27 estuaries in the region and we recognise that we need to look after these places if we want to maintain a good whitebait fishery. We also work with care groups and local communities throughout our region to help re-establish suitable habitat for inanga spawning.

A spawning site for inanga in the Oterei Stream in the Wairarapa. We found eggs in the vegetation marked with the white dotted line.

Taxonomy

    Scientific name: Galaxias maculates (Jenyns)
    Synonyms: Galaxias attenuatus
    Popular Common names: inanga, whitebait.
    Other common names: cowfish, milkfish, minnow.

    Kingdom: Animalia
    Phylum: Chordata
    Class: Actinopterygii (ray/finned fishes)
    Order: Osmeriformes (smelts)
    Family: Galaxiidae
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