Banded kōkopu

Species of fish
the general article about kōkopu

The banded kōkopu (Galaxias fasciatus) is a galaxiid of the genus Galaxias, found only in New Zealand, including the Chatham and Stewart/Rakiura islands. It commonly grows to 20–25 cm, but has been recorded growing to around 30 cm. Juvenile banded kōkopu are good climbers and can climb up waterfalls and other vertical surfaces by moving into the splash zone and wriggling up the surface, using the water surface tension and their large downturned fins for grip.

Banded kōkopu are a stout bodied fish, with a large head and mouth. The fish are strong, rounded and fleshy. Like other galaxiids, the dorsal and anal fins are positioned close to the tail fin, which is short and square. The caudal peduncle is short and deep, with thick fleshy flanges which join the tail fin. Adults are usually a dark, earthy brown or olive brown, with pale yellow vertical bands along the body. The belly is light coloured and unpatterned. Although the bands change as the fish ages, the placement and shape of the bands are consistent enough to be used for individual identification over several years. Medium and juvenile giant kōkopu can sometimes be mistaken for banded kōkopu, as they can also develop vertical stripes. The easiest way to differentiate between the two species is that banded kōkopu have a white or silver mark immediately behind the operculum, above the pectoral fin, and giant kōkopu do not. As the flood recedes the eggs are left to develop out of the water; the high humidity provided by the vegetation keeps them moist. Banded kōkopu can live for at least nine years, possibly longer, and spawn multiple times over their lifetime.

Banded kōkopu are largely nocturnal, and may be easily and unobtrusively observed night, ideally using red light. Banded kōkopu may also be observed during the day if undisturbed. Juvenile banded kōkopu are one of five species of galaxiid caught and eaten as whitebait.