Introduction

Spotted galaxias (Galaxias truttaceus) are a largish, primarily-freshwater galaxias species found in southern Australia. Chordates ( Phylum Chordata) are a group of Animals that includes the Vertebrates together with several closely related Invertebrates The Actinopterygii (the plural form of Actinopterygius) comprise the class of the ray-finned fishes. Osmeriformes is an order of Ray-finned fish that includes various kinds of Smelts Noodlefishes and the odd-looking Barreleyes The The Galaxiids are a family of mostly small freshwater Fish. Representatives occur throughout the southern hemisphere including South Africa, South America Galaxiinae is a subfamily of fishes It contains four genera For a topic outline on this subject see List of basic Australia topics. Spotted galaxias are perhaps the most beautiful of the Australian galaxias species. They are a somewhat tubular, deep-bodied fish, with a dusky brownish-red colouration overlain with dark, haloed spots, dramatic black edges to dorsal, anal and pelvic fins, and a dark diagonal stripe through the eye. A dorsal fin is a Fin located on the backs of some Fishes Whales Dolphins and Porpoises as well as the (extinct The Anatomy of Fish is primarily governed by the physical characteristics of Water, which is much denser than air holds a relatively small amount of dissolved The Anatomy of Fish is primarily governed by the physical characteristics of Water, which is much denser than air holds a relatively small amount of dissolved

Spotted galaxias. The characteristic base colouration and black edges to the fins are not particularly noticeable in this photo.

Spotted galaxias has a very wide distribution, being found in southern Victoria, all of Tasmania, offshore islands in between, as well as south-west Western Australia. Tasmania is an Australian island and state of the same name It is located south of the eastern side of the Continent, being separated from it by Bass Western Australia is a state occupying the entire western third of the Australian continent.

On the mainland spotted galaxias is generally recognised as a freshwater fish species with a marine larval phase (larvae are swept out to sea and return to freshwater habitats as early stage juveniles), and thus only found in coastal rivers. Spotted galaxias generally are generally found in coastal rivers in Tasmania as well, however natural landlocked populations do occur in some freshwater lakes in Tasmania.

Spotted galaxias were assumed not to be native to the Murray-Darling river system, however records of native fish fauna compiled by William Blandowski in the 1850s suggest the species did historically occur in the Murray-Darling river system. The Murray-Darling Basin is 3375km long drains one-seventh of the Australian land mass and is currently by far the most significant agricultural area in Australia Wilhelm (William Blandowski ( January 21 1822 - December 18 1878) a German zoologist and mining engineer was born in Gleiwitz The Murray-Darling Basin is 3375km long drains one-seventh of the Australian land mass and is currently by far the most significant agricultural area in Australia This may cause a re-evaluation of the spotted galaxias specimens occasionally recovered in the Murray-Darling river system, which until now were assumed to be accidental translocations via the Snowy Mountains Hydro-Electric Scheme. The Snowy Mountains Scheme is a Hydroelectricity and irrigation complex in south-east Australia

Habitat, Diet, Reproduction

Spotted galaxias, in their juvenile and adult stages, inhabit coastal rivers at low to medium altitude. They prefer cool, flowing rivers in forested catchments with excellent riparian vegetation, good water quality and cover in the form of boulders, sunken logs and overhanging banks.

Spotted galaxias are a predatory fish, feeding in the currents or "drift" similar to exotic trout species. Trout is the common name given to a number of Species of Freshwater Fish belonging to the Salmonidae family Their diet consists mainly of aquatic and terrestrial invertebrates.

Spawning occurs in winter in rivers. Larvae are swept out to sea and return and migrate back up rivers as early-stage juveniles which initially do not resemble adult fish. Returning juveniles sometimes intercepted by humans as whitebait, and were severely overfished in previous decades. Landlocked lake populations spawn in spring.

Human Use

Before the introduction of exotic trout species to Australia, an introduction that has caused severe problems for the conservation of Australian native fish, spotted galaxias were keenly fished for by early Australian anglers using fly-fishing gear. Trout is the common name given to a number of Species of Freshwater Fish belonging to the Salmonidae family The species was appreciated for its beauty, its willingness to take wet and dry flies, its game fighting ability on very light tackle, and its relatively large size by galaxias standards, sometimes reaching 30 cm, and commonly 20 cm. (Spotted galaxias appear to have had a larger average size before the introduction of exotic trout species. ) A handful of fly-fishers in Australia are now re-discovering the pleasure of fly-fishing for this magnificent native fish with ultra-light fly-fishing tackle.

As mentioned above, early-stage juveniles returning to estuaries were and sometimes still are netted as white bait, which are caught for human consumption.

With their beautiful appearance spotted galaxias have immense potential as aquarium fish, but do require cool water.

Conservation

Spotted galaxias are threatened by dams and weirs blocking migration and fragmenting river habitats, irresponsible forestry and farming practices that degrade river environments through siltation and other effects, and competition and predation by exotic trout species.

In Tasmanian rivers spotted galaxias numbers are severely depressed when exotic trout species are present (Ault & White, 1994). This is a common phenomena; galaxias species that manage to survive the presence of exotic trout (many species do not) such as spotted galaxias are forced into sub-optimal feeding locations, feeding times and diets by aggressive competition from exotic trout species (McDowall, 2006). Galaxias populations in such situations tend to display lower than normal growth, size and fecundity, raising concerns for their long-term future (McDowall, 2006).

In southern Victoria however many recreational fishermen report that spotted galaxias are found only in the few trout-free streams remaining. Spotted galaxias appear to reach a larger maximum size in these few trout-free streams than in Tasmania. A lack of exotic-trout-free habitat reserved for spotted galaxias and other native fish species in south-eastern Australia generally is a major concern.

References

• Galaxias truttaceus (TSN 623458). Integrated Taxonomic Information System. Integrated Taxonomic Information System ( ITIS) is a partnership designed to provide consistent and reliable information on the Taxonomy of biological Species Retrieved on 22 May 2007. Events 334 BC - The Greek army of Alexander the Great defeats Darius III of Persia in the Battle of the Granicus. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
• "Galaxias truttaceus". FishBase. FishBase is a comprehensive Database of information about Fish. Ed. Ranier Froese and Daniel Pauly. 5 2007 version. N. p. : FishBase, 2007.
• Ault, T. R. and White, R. W. G. (1994) Effects of habitat structure and the presence of brown trout on the population density of Galaxias truttaceus in Tasmania, Australia. Transactions of the American Fisheries Society 123: 939–949.
• McDowall, R. M. (ed. ) (1996) Freshwater fishes of south-eastern Australia. Reed Books, Sydney.
• McDowall, R. M. (2006) Crying wolf, crying foul, or crying shame: alien salmonids and a biodiversity crisis in the southern cool-temperate galaxioid fishes? Rev Fish Biol Fisheries 16: 233–422.

External links

• Native Fish Australia – Spotted galaxias page