Shannon Galaxias, Paragalaxias dissimilis (Regan 1906)

Other Names: Dissimilar Jollytail, Eel-gudgeon, Shannon Galaxias, Shannon Paragalaxias

Shannon Galaxias, Paraglaxias dissimilis. Source: J. Patil / Inland Fisheries Service, Tasmania. License: CC By Attribution-NonCommercial-ShareAlike

Summary:

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.

Cite this page as:

Gomon, M.F. & Bray, D.J. 2025, Paragalaxias dissimilis in Fishes of Australia, accessed 23 May 2025, https://fishesofaustralia.net.au/Home/species/3394

Shannon Galaxias, Paragalaxias dissimilis (Regan 1906)

More Info

Distribution	Endemic to Great Lake, Shannon Lagoon, Penstock Lagoon and the headwaters of the Shannon River. on the the Central Plateau of Tasmania. The Shannon and Penstock lagoons are artificial impoundments and their populations most likely originated from Great Lake. Prefers structurally complex habitats such as rocky substrates, algal (charophyte) beds, aquatic macrophytes and woody debris. The species is most active at night.
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, gastropod molluscs, algae and eggs of other galaxiid fishes.
Biology	The species is non-diadromous, and individuals attain sexual maturity at one year of age. Female fecundity typically ranges from 30-450 eggs annually. Spawning occurs in the austral spring-summer from October to February, with peak spawning activity occurring in November to mid-January. 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	IUCN Red List : Endangered Threats include declines in habitat quality and availability due to low water levels or unseasonal water level fluctuations associated with hydro-electric power generation and the impacts of global climate change. In addition, all waters occupied by this species are inhabited by Brown Trout, and predation and competition from this species are recognised as a significant threatening processes.
Remarks	Nocturnally active.
Similar Species	Differs from Paragalaxias eleotroides in having large sensory pores on the head, particularly two pairs under the lower jaw.
Etymology	The specific name is from the Latin dissimilis (= unlike, dissimilar), in reference to the six-rayed pelvic fins of this species, compared with seven rays in its presumed congeners in Galaxias.
Species Citation	Galaxias dissimilis Regan 1906, Proceedings of the Zoological Society of London 1905(2, 2): 383. Type locality: ? New South Wales (presumably in error for Tasmania).
Author	Gomon, M.F. & Bray, D.J. 2025
Resources	Atlas of Living Australia Australian Faunal Directory Catalog of Fishes

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.

Andrews, A.P. 1976. A revision of the family Galaxiidae (Pisces) in Tasmania. Australian Journal of Marine and Freshwater Research 27: 297-349. https://doi.org/10.1071/MF9760297

Freeman, R. 2019. Paragalaxias dissimilis. The IUCN Red List of Threatened Species 2019: e.T122904093A123382191. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T122904093A123382191.en. Accessed on 21 May 2025.

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. https://doi.org/10.1071/MF9820999

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.

Hardie, S.A., Jackson, J.E., Barmuta, L.A. & White, R.W.G. 2005. Status of galaxiid fishes in Tasmania, Australia: conservation listings, threats and management issues. Aquatic Conservation: Marine and Freshwater Ecosystems 16(3): 235-250

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. https://doi.org/10.1023/A:1007421316768

McDowall, R.M. & Frankenberg, R.S. 1981. The galaxiid fishes of Australia. Records of the Australian Museum 33(10): 443-605 figs 1-47. https://doi.org/10.3853/j.0067-1975.33.1981.195

McDowall, R.M. & Fulton, W. 1978. A revision of the genus Paragalaxias Scott (Salmoniformes : Galaxiidae). Australian Journal of Marine and Freshwater Research 29(1): 93-108. https://doi.org/10.1071/MF9780093

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 https://doi.org/10.1071/MF9780659

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. & Schmida, G.E. 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 http://dx.doi.org/10.11646/zootaxa.3898.1.1

Regan, C.T. 1906. A revision of the fishes of the family Galaxiidae. Proceedings of the Zoological Society of London 1905(2, 2): 363-384 figs 10-13. See ref at BHL

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 (described as Paragalaxias shannonensis, type locality Shannon River below the road bridge over the Shannon, between the Great Lake hydro-electric dam at Miena and the Shannon Lagoon, Tasmania)

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