Flathead galaxias (Australia)
The flathead galaxias (Galaxias rostratus) is a freshwater fish found in lowland rivers and streams and associated billabongs, backwaters, etc. of the southern Murray-Darling river system in Australia.
Flathead galaxias continue a pattern found in Murray-Darling native fish of speciation into upland and lowland habitats. Flathead galaxias are found in lowland habitats, while the mountain galaxias species complex, containing at least seven species of Galaxias (research is ongoing) are found in upland habitats, as well as "midland" or upland/lowland transitional habitats.
The fish is similar in appearance to the common galaxias, except with a distinctly flattened head, larger eyes and longer snout. It has an olive green back and sides with indistinct grey to green blotches and silvery bottom. Adults are commonly 9 cm but found up to 12 cm long.
Serious concerns exist for flathead galaxias. They, along with a number of other small native forage fish, are disappearing from vast tracts of the Murray-Darling basin. The species is considered extinct in South Australia. Along with river regulation, destruction of water clarity and submergent macrophytes ("water weed") by exotic, illegally introduced common carp (Cyprinus carpio) appear to be having a devastating effect on this species. Many or all of the small native forage fish of the southern Murray-Darling system apparently used these weeds beds for shelter, feeding, and spawning sites.
- Gomon, Martin; Bray, Dianne. "Flathead Galaxias, Galaxias rostratus". Fishes of Australia. Retrieved 14 September 2014.
- Wager (1996). "Galaxias rostratus". IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature. Retrieved 11 May 2006. Listed as Vulnerable (VU A1c v2.3)
- "Galaxias rostratus". Integrated Taxonomic Information System. Retrieved 11 March 2006.
- Froese, Rainer and Pauly, Daniel, eds. (2005). "Galaxias rostratus" in FishBase. 10 2005 version.