Story: Freshwater fish

Page 5. Bullies, smelt and grayling

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Bullies

After galaxiids, bullies form the second largest native fish family, known as Eleotridae. They are often called cockabullies, but these are a different family of mostly marine fish. Seven species are widespread across the country. Small fish seen around a lake shore will probably be bullies, most likely the species known as common bullies.

Bullies are mostly small, with adults commonly around 10 centimetres long. They have scales and two dorsal fins. The redfin bully male has vivid red coloration, especially on the tail and dorsal and anal fins.

These fish are found almost everywhere, although mostly at low elevations. This is partly because the young of four of the seven species spend their first few months at sea: the adults can be found only in places that are accessible from the sea.

They have interesting breeding habits. The male establishes his territory, usually in a cavity beneath a large rock, and while guarding it, tends to turn a darker colour. The spawning female is lured into the territory and deposits the eggs, one by one, forming a single layer on the underside of a rock. The male, following along, fertilises them. He then guards them until they hatch.

Smelt

New Zealand has two fish of the Retropinnidae family. These are the common smelt (Retropinna retropinna) and Stokell’s smelt (Stokellia anisodon). Although smelt have a very strong cucumber odour when they are first captured, the name smelt has nothing to do with this. It is an ancient word for silvery – referring to their colour.

Growing to around 10 centimetres, smelt move into lowland rivers from the sea as mature adults to spawn – often being caught towards the end of the whitebait fishing season, in spring. They are very fragile, dying within a minute or two if handled.

The smelt populations in some inland lakes, especially in the central North Island, belong to the same species, but have abandoned migrations to and from the sea, spending their whole lives in fresh water.

Grayling (Upokororo)

Closely related to the smelt was a fish, now extinct, known as upokororo (Prototroctes oxyrhynchus). The early settlers called it grayling, but it is not related to the true grayling of the northern hemisphere.

It is New Zealand’s only extinct freshwater fish species, having disappeared by the 1920s for reasons that have not been identified. It was among the larger native fish – probably growing up to 45 centimetres – and looked like an overgrown smelt.

How to cite this page:

Bob McDowall, 'Freshwater fish - Bullies, smelt and grayling', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/freshwater-fish/page-5 (accessed 19 November 2018)

Story by Bob McDowall, published 24 Sep 2007