Galaxias johnstoni

Galaxias johnstoni, also known as the Clarence galaxias, is a small freshwater fish belonging to the family Galaxiidae, a group of scaleless fishes found across the Southern Hemisphere. Like other galaxiids, it has an elongated body, a broad flattened head, and lacks the scales typical of many other fish groups. It feeds on aquatic invertebrates and plays a role in freshwater food webs as both predator and prey.

As a stream-dwelling species, it also serves as an indicator of water quality and habitat condition.

This species is restricted to a small area of the Clarence River catchment in Tasmania, Australia. It inhabits cool, clear permanent rivers and streams, as well as associated wetland habitats including bogs, marshes, swamps, and fens, and permanent freshwater lakes. Its highly restricted range makes it particularly vulnerable to localized disturbances.

Threats to Galaxias johnstoni include altered fire regimes and fire suppression activities, which can affect catchment vegetation and water quality. Invasive species, including introduced predatory and competitive fish, pose an ongoing risk to native galaxiid populations. Habitat alteration and shifting environmental conditions, along with periodic droughts that reduce stream flow and connectivity, further threaten the limited habitat this species depends on.

Conservation measures include population monitoring within its restricted range and management strategies aimed at limiting the spread of invasive fish into occupied habitat. Protection of catchment areas from disturbance also forms part of broader efforts to maintain suitable water conditions.

The population is currently assessed as stable, though its restricted distribution and reliance on a single river system mean the species remains vulnerable to environmental change, invasive species incursions, and stochastic events such as fire or drought.