Shannon Galaxias, Paragalaxias dissimilis (Regan 1906)
Shannon Galaxias, Paraglaxias dissimilis. Source: J. Patil / Inland Fisheries Service, Tasmania. License: CC By Attribution-NonCommercial-ShareAlike
A small dark greyish, olive-brown to almost blackish galaxias becoming olive-gold below, with saddle-like markings along the back that extend down the sides.
Shannon Galaxias, Paragalaxias dissimilis (Regan 1906)
More Info
|
Distribution |
Endemic to the Central Plateau of Tasmania, and found only in Great Lake, Shannon Lagoon, Penstock Lagoon and the headwaters of the Shannon River. The Shannon and Penstock lagoons are artificial impoundments and these populations may have originated from Great Lake. The Shannon Galaxias inhabits lake shores and stream margins, usually sheltering among rocky areas, aquatic vegetation and debris near the bottom. |
|
Features |
Dorsal-fin rays 14-15; Anal-fin rays 8-10 (usually 9 or 10); Pectoral-fin rays 12-14 (usually 13 or 14); Pelvic-fin rays 6; Gill rakers (1st arch) 15-18; Vertebrae 41-44. Body elongate, bullet-shaped, depth at anus 12.8-15.2% SL; head long, flattened; snout long; mouth large, reaching back to the eye; jaws equal; lateral canine teeth absent from jaws; sensory pores on head very large; lateral line present; open pores present on head, rows of laterosensory papillae on head and tail base Dorsal fin relatively high and long-based, origin above level of pelvic fins; pectoral fins large; caudal fin emarginate. |
|
Size |
To 7.5 cm SL, commonly to 5.5cm. |
|
Colour |
Colour varies depending on the habitat: dark grey, olive-brown or blackish above with saddle-like markings extending down the sides; belly paler; fins olive-brownish to transparent. |
|
Feeding |
Feed on insects and their larvae, small crustaceans, algae and eggs of other galaxiids. |
|
Biology |
The species is non-diadromous. Individuals mature at one year old. Females spawn clusters of up to 500 eggs in nearshore crevices and interstitial spaces between rocks during summer. The eggs are 2mm in diameter and are guarded until the larvae hatch after about two weeks. Larvae hatch at about 8 mm after about 2 weeks. They are planktonic for several months before settling out around the shore after about 6 months. |
|
Conservation |
|
|
Remarks |
Nocturnally active. |
|
Similar Species |
Differs from Paragalaxias eleotroides in having large sensory pores on the head, particularly two pairs under the lower jaw. |
|
Species Citation |
Galaxias dissimilis Regan, 1906, Proc. Zool. Soc. Lond. 1905(2, 2): 383. Type locality: New South Wales (presumably in error for Tasmania). |
|
Author |
Gomon, M.F. & Bray, D.J. 2018 |
|
Resources |
Shannon Galaxias, Paragalaxias dissimilis (Regan 1906)
References
Allen, G.R. 1989. Freshwater Fishes of Australia. Neptune, New Jersey : T.F.H. Publications 240 pp., 63 pls.
Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field Guide to the Freshwater Fishes of Australia. Perth : Western Australian Museum 394 pp.
Fulton, W. 1982. Observation on the ecology of four species of the genus Paragalaxias (Pisces:Galaxiidae) from Tasmania. Australian Journal of Marine and Freshwater Research 33: 999-1016.
Fulton, W. 1990. Tasmanian freshwater fishes. Fauna of Tasmania Handbook No. 7 Hobart : University of Tasmania, Fauna of Tasmania Committee, in association with the Inland Fisheries Commission of Tasmania 80 pp.
Hardie, S.A., Macfarlane, K.R. & Barmuta, L.A. 2011. Life histories of galaxiid fishes in Arthurs Lake and Great Lake, Tasmania, and effects on water level fluctuations on their populations. Hydro Tasmania, Hobart. 200 pp.
Humphries, P. & Walker, K. (eds). 2013. Ecology of Australian freshwater fishes. CSIRO Publishing. 440 pp.
Last, P.R., Scott, E.O.G. & Talbot, F.H. 1983. Fishes of Tasmania. Hobart : Tasmanian Fisheries Development Authority 563 pp. figs.
McDowall, R.M. 1998. Phylogenetic relationships and ecomorphological divergence in sympatric and allopatric species of Paragalaxias (Teleostei: Galaxiidae) in high elevation Tasmanian lakes. Environmental Biology of Fishes 53: 235-257.
McDowall, R.M. & Frankenberg, R.S. 1981. The galaxiid fishes of Australia. Records of the Australian Museum 33(10): 443-605 figs 1-47.
McDowall, R.M. & Fulton, W. 1978. A revision of the genus Paragalaxias Scott (Salmoniformes : Galaxiidae). Aust. J. Mar. Freshwat. Res. 29(1): 93–108.
McDowall, R.M. & Fulton, W. 1978. A further new species of Paragalaxias Scott (Salmoniformes : Galaxiidae), from Tasmania with a revised key to the species. Australian Journal of Marine and Freshwater Research 29(5): 659-665 figs 1-4
McDowall, R.M. & Fulton, W. 1996. Family Galaxiidae in McDowall, R.M. (ed.) Freshwater Fishes of South-eastern Australia. Sydney : Reed Books 247 pp.
Merrick, J.R. & G.E. Schmida. 1984. Australian freshwater fishes: biology and management. Griffin Press Ltd., South Australia. 409 p.
Raadik, T.A. 2014. Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species. Zootaxa 3898(1): 1-198
Regan, C.T. 1906. A revision of the fishes of the family Galaxiidae. Proc. Zool. Soc. Lond. 1905(2, 2): 363–384 figs 10–13.
Scott, E.O.G. 1935. On a new genus of fishes of the family Galaxiidae. Papers and Proceedings of the Royal Society of Tasmania 1934: 41-46 figs 1-2 pl. 3 (as Paragalaxias shannonensis)
Stokell, G. 1950. A revision of the genus Paragalaxias. Records of the Queen Victoria Museum, Launceston 3(1): 1-4
Unmack, P.J. 2001. Biogeography of Australian freshwater fishes. Journal of Biogeography 28: 1053-1089
