Giant kokopu
Encyclopedia
For a general article about all 3 kokopu
Kokopu
Kokopu is a common name used for three species of fish of the genus Galaxias. They are found in the rivers, lakes and swamps of New Zealand for which they are endemic. Kokopu are galaxiids and like others members of that family lacks scales and has a thick, leathery skin covered with mucus. Kokopu...

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The giant kokopu, Galaxias argenteus, is a galaxiid
Galaxiid
The Galaxiidae, also known by the anglicised name as galaxiids, are a family of mostly small freshwater fish in the southern hemisphere. The majority of species live in Australia or New Zealand, some are also found in South Africa, South America, Lord Howe Island, New Caledonia and the Falkland...

 of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Galaxias
Galaxias
Galaxias is the common name for a large group of smallish, highly successful freshwater fish in the Galaxias genus and Galaxiidae family. Galaxias are restricted to the southern hemisphere, and generally only occur in temperate latitudes; only one species is known from sub-tropical habitat...

, found only in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. It grows to a length of up to 45 cm and is the largest member of the Galaxiidae family. It is also one of the five species that occur in the whitebait
Whitebait
Whitebait is a collective term for the immature fry of fish, typically between 25 and 50 millimetres long. Such young fish often travel together in schools along the coast, and move into estuaries and sometimes up rivers where they can be easily caught with fine meshed fishing nets...

 runs that enter New Zealand rivers each spring. Due to the large size of giant kokopu, it is the only galaxiid species possible of out competing trout, and as such it is thought that the presence of g. argentenus could add to a streams resistance to brown trout invasion

The single dorsal
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 and anal fins are large, rounded, and set back close to the large square caudal fin. The pelvic fins are also large. Like all galaxiids it lacks scale
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...

s and has a thick, leathery skin covered with mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

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