T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Dune lake galaxias (Galaxias gracilis)

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Osmeriformes
Family: Galaxiidae
Subfamily: Galaxiinae
Genus: Galaxias
Species: G. gracilis
Binomial name: Galaxias gracilis
Common name: Dune lake dwarf inanga. Dune lake galaxias

Galaxias gracilis looks like a small inanga and is closely related to inanga. It is a landlocked galaxiid present in only thirteen lakes on the west coast of the North Island within 50 km of Dargaville, and in Lake Ototoa on the South Kaipara Head, where it was introduced in 1986. It is the smallest member of the Galaxiidae family in New Zealand. Specimens of over 80 mm in length are rare, and mature adults may be only 40 mm
Juveniles school around the lake edges where rushes and macrophytes provide shelter from predators. They feed on zooplankton in open waters at night. Adults occur in deeper water near the middle of the lake and return to the littoral zone at night to feed on the larger invertebrates present there.

Dwarf inanga populations have declined over the past 30 years, and it is now considered to be a threatened species. The introduction of rainbow trout into some of the lakes it inhabits (especially the Kai Iwi lakes) was initially blamed for this decline, as trout are known to eat inanga. However, removal of trout from one lake did not increase the abundance of dwarf inanga and, up until 2000, it was abundant in Lake Ototoa which was routinely stocked with trout. Gambusia affinis is now thought to be responsible for its scarcity in Lakes Taharoa and Waikere, and for its extinction in Lake Kai Iwi.  (Text thanks to https://www.niwa.co.nz). 

Distribution map of Galaxias gracilis (Red areas)

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/