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
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Galaxiiformes
Family: Galaxiidae
Genus: Galaxias
Species:
G. rostratus
Binomial name
Galaxias rostratus

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.

Morphology

The fish is similar in appearance to the common galaxias, except with a distinctly flattened head, larger eyes and longer snout.[2] 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.

Conservation

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.[2] 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.

References
  1. Gilligan, D., Pearce, L. & Raadik, T. (2019). "Galaxias rostratus". The IUCN Red List of Threatened Species. IUCN. 2019: e.T8814A129041409.CS1 maint: multiple names: authors list (link)
  2. Gomon, Martin; Bray, Dianne. "Flathead Galaxias, Galaxias rostratus". Fishes of Australia. Retrieved 14 September 2014.
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