New Zealand status: Native
Conservation status: Declining
International conservation status: Least concern (IUCN)
Found in: New Zealand’s North, South, Stewart Island/Rakiura, Chatham Island/Rēkohu/ Wharekauri, subantarctic Auckland and Campbell Islands and in Australia.
Threats: Habitat disturbance and modification
Appearance and size
Kōaro (Galaxias brevipinnis) have distinctive tube-shaped bodies. Their sides and back are covered in a pattern of light patches and bands, and shine with iridescence in bright light.
They commonly grow to about 160–180 mm but can reach 290 mm. Kōaro live for about 15 years.
Where they live
Kōaro are found in many fast-flowing, cool, tussock or forest streams. They are able to climb very steep waterfalls using special broad fins that have a grippy texture underneath. This climbing ability allows them to travel as far as 400 km inland and climb as high as 1300 m.
Kōaro also form land-locked populations in lakes, including Lakes Taupō, Rotoaira, Manapouri, Tekapo, Pukaki, Wānaka and many of the Rotorua lakes. Their numbers in these lakes fell significantly when trout were introduced, because trout eat native fish. Introduced smelt have also caused their numbers to decline further or become extinct in some lakes.
Lifecycle
Kōaro are migratory galaxiids and move between streams, rivers and the sea during their lifecycle. They are one of the six species of native fish caught as whitebait as they enter rivers and streams to begin their upstream migration.
Inanga lifecycle
Image: DOC