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Galaxias fuscus (Family Galaxiidae)

Barred Galaxias

Distribution

Distribution:

The Barred Galaxias is found only in the very upper reaches of the Goulburn River system in central Victoria. All sites are above 400 m in elevation (VIC).

Features:

Barred Galaxias is a small cylindrical, scaleless fish that grows to 160 mm. Adults are a dusky light brown to orange with up to 10 large partial or complete ovoid black bars on the sides. There is no mottling of the sides or the dorsal surface. The head is broad and bulbous, with a large eye and mouth gape, and the pelvic and pectoral fins are large. They have one dorsal fin set far back along the body. Juveniles are brownish in colour, and develop black bars in their second year.

Ecology/Way of Life:

The Barred Galaxias is a non-migratory species. It is found in clear flowing, small (1–4 m wide) shallow streams with boulder, pebble, gravel and sand substrates. These streams usually have high loads of timber in the channels forming important structural habitat, are cool (less than 15°C during summer), and well oxygenated. Barred galaxias prefer slow-flowing deep pools adjacent to areas of faster flow, and they have been found in elevation up to approximately 1200 m. Diet is poorly known, but is thought to consist of terrestrial insects and other aquatic macroinvertebrates. Spawning occurs during August to October, triggered by an increase in day length and water temperature. Spawning can occur in water temperatures of 2°C, when catchments at higher elevations are covered in snow. Females lay up to 500 large, adhesive eggs, which have been found stuck to the underside of boulders in fast flowing water. Newly hatched young (12 mm in length) have been collected in early December.

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Interaction with Humans/Threats:

The major threat to this species is the negative interaction with alien Brown and Rainbow Trout (Salmo trutta and Oncorhynchus mykiss). Predation by trout on the first four to five year classes of Barred Galaxias, followed by competition for food and space with older age classes eventually causes the local extinction of Barred Galaxias in less than ten years in newly invaded streams. Barred Galaxias populations remain protected from trout invasion above natural waterfalls in remote areas, though newly opened forestry roads into these areas means that with improved access, there is a greater chance that trout can easily be translocated above the barriers by humans.

Other Comments:

Galaxias fuscus was named by Mack in 1936. The name is derived from galax a Greek word meaning milky (in reference to the milky way); and fusc a Latin word meaning brown, dark, dusky.

The Barred Galaxias is a part of the Mountain Galaxias (Galaxias olidus) species complex. Continuing work on the Mountain Galaxias complex indicates that there are a number of additional species that will be elevated to species status in addition to the Barred Galaxias.

Further Reading:

Allen, G. R., Midgley, S. H. & Allen, M. (2002). Field Guide to the Freshwater Fishes of Australia. Western Australian Museum. Perth. 394pp.

Koehn, J. D. & Raadik, T. A. (1995). Barred Galaxias Galaxias olidus var. fuscus. Action Statement No. 65. Department of Conservation and Natural Resources, Victoria.

Raadik, T. A. (1995). A research recovery plan for the Barred Galaxias in south–eastern Australia. Flora and Fauna Technical Report No. 141. Department of Conservation and Natural Resources, Victoria.

Raadik, T. A., Saddlier, S. R. & Koehn, J. D. (1996). Threatened fishes of the world: Galaxias fuscus Mack, 1936 (Galaxiidae). Environmental Biology of Fishes 47: 108.

Shirley, M. J. & Raadik, T. A. (1997). Aspects of the ecology and breeding biology of Galaxias fuscus Mack, in the Goulburn River system, Victoria. Proceedings of the Royal Society of Victoria 109: 157–166.

Acknowledgments:

Text: Tarmo A. Raadik. Distribution map: Peter J. Unmack. Photographers: Tarmo A. Raadik & Neil Armstrong.

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