The dwarf galaxias, Galaxias divergens, 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 the lower North Island

North Island

The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

 and upper South Island

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

 of 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 9 cm.

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 about two thirds of the way along the body. 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...

.

The dwarf galaxias has six pelvic fin rays, which distinguishes it from most other galaxiids which have only five.

Spawning occurs from March to May and also from October to November. They live on a variety of aquatic insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, especially mayflies and midge

Midge (insect)

Midges comprise many kinds of very small two-winged flies found world-wide. The term does not encapsulate a well-defined taxonomic group, but includes animals in several families of Nematoceran Diptera. While some midges are vectors for disease, many others play useful roles as prey items for...

s. They are non-diadromous and therefore do not have a marine phase and are not part of 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...

catch.