The Kokopu is a rather stout tubular fish found in rivers, lakes and swamps generally near the coastal environment. It is unique to New Zealand and our coastal islands such as the Chatham's though related species are found in Australia, South America and South Africa. The Kokopu belongs to the galaxiid fish family and like other galaxiids lacks scales and has a thick, leathery skin that is covered with an abundant coat of mucous. They feed mostly on invertebrates (aquatic insects) that inhabit the streambed, but also eat terrestrial insects that fall onto the water surface. The presence of food has a critical influence on their survival. They move into the open at night to feed.

The Kokopu are most commonly found in smaller streams with plenty of cover within the stream channel such as logs, tree roots, overhanging boulders, raupo, flax and bushes but they are also present in swampy areas and some larger waterways.

There are three known species of Kokopu in New Zealand and all of these have been found recently in the Auckland region.

Known species of Kokopu in New Zealand

The Banded Kokopu (Galaxias fasciatus)

The Banded Kokopu (pictured above) is the most common of the three and is often seen in small bush clad streams near suburban homes especially in streams that drain lowland or coastal hills throughout the Auckland region. Banded kokopu commonly grow to over 200 mm.

The Giant Kokopu (Galaxias argenteus)

The Giant Kokopu, also known as the native trout is the largest of the three species and is found throughout New Zealand in streams that are only a short distance from the sea. Giant kokopu have been recorded up to 2.3 kg, at a length of 50 cm. Although they are found in Auckland they are less common than the Banded Kokopu.

The Shortjawed Kokopu (Galaxias post vectis)

The Shortjawed Kokopu is the least common species. Though rarely encountered in New Zealand in the past, this species has recently been sited in the Waitakere Ranges and appears to be coming more numerous.

The Kopopu lifecycle

Male Kokopu generally mature after two years, while the females take up to four years. Kokopu are known to live between five and 10 years, but a few large specimens are estimated to be over 21 years old.

The Kokopu spawn during April among riparian vegetation or in high stream flow conditions such as a flood or spring tide, in leaf litter beside the stream. The eggs hatch about 30 days after being laid, and are carried downstream where they spend a short period of time in the sea. Juvenile kokopu return to the streams among the whitebait catch in October after four to five months in the sea. These juveniles quickly move upstream to mature in the stream habitat frequented by the adult of each species.

Three of the five species commonly captured by white baiters are Kokopu.