Freshwater Fishes

Australia’s freshwater fish fauna, with just over 280 native species, is the smallest for any continent of a similar size. The USA, for example, has almost 1000 freshwater fishes (including non-native species).

The small number of species found in our waters is partly because Australia is the driest continent on earth. Rainfall is sporadic over much of the continent, and fishes cannot live in many of the desert regions of South Australia and Western Australia. Most freshwater species are found in tropical or subtropical regions.

Both primary freshwater species and secondary freshwater species are found in Australia. Primary freshwater fishes evolved entirely in freshwater, whereas secondary freshwater fishes are derived from marine ancestors.

In contrast to other parts of the world, Australia only has three primary freshwater fishes and these are thought to have evolved before the breakup of the supercontinent Gondwana, between 125 and 150 million years ago. These are the Australian Lungfish (Neoceratodus forsteri) and the two species of Saratoga (Scleropages jardinii and S. leichhardti).  

Other freshwater fish groups with Gondwanan origins are the families Retropinnidae, Galaxiidae, Aplochitonidae and Percichthyidae. Although the unique Salamanderfish (Lepidogalaxias salamandroides) belongs to an ancient lineage, its origins and relationships continue to be debated.

Many of Australia’s secondary freshwater fishes, especially those found in warmer areas, evolved from marine ancestors that colonised Australia well after the breakup of Gondwana. Most are related to groups found in the tropical Indo-Pacific, and these include the catfishes (Ariidae and Plotosidae), the hardyheads, rainbowfishes and blue-eyes (Atherinidae, Melanotaeniidae and Pseudomugilidae), the grunters (Terapontidae) and the gobies and gudgeons (Gobiidae and Eleotridae).

In Australia (and New Guinea), catfishes, terapontid grunters and eleotrid gudgeons have undergone considerable speciation in freshwater, while they mostly inhabit marine or estuarine environments elsewhere.

While the primary and secondary freshwater species are restricted to freshwater for all or part of their lives, other estuarine or marine fishes may enter the lower reaches of freshwater streams and rivers, and some venture well upstream.  

Some freshwater fishes complete their entire life cycle in fresh water, whereas others are diadromous, spending a part of their lives in estuarine or marine environments. A few migrate from the sea as adults to breed in freshwaters, while others migrate from freshwater to breed in estuaries or further seawards. The larvae of other species are carried well out to sea where they develop before migrating back to freshwater as immature juveniles (whitebait).

References

Allen, G. R. & Cross, N. J. 1982. Rainbowfishes of Australia and Papua New Guinea. T.F.H. Publications, New Jersey. 141pp.

Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field guide to the freshwater fishes of Australia. Western Australia Museum, Perth, 394 pp.

Corfield, J., Diggles, B., Jubb, C., McDowall, R. M., Moore, A., Richards, A. & Rowe, D. K. 2008. Review of the impacts of introduced ornamental fish species that have established wild populations in Australia. Report prepared for the Australian Government Department of the Environment, Water, Heritage and the Arts.

Davis AM, Pusey BJ & Pearson, RG. 2011. Trophic ecology of terapontid fishes (Pisces : Terapontidae) : the role of morphology and ontogeny. Marine and Freshwater Research 63(2): 128-141.

Gilligan, D. 2005. Fish communities of the Lower Murray-Darling catchment: status and trends. NSW Department of Primary Industries - Fisheries Final Report Series, No. 83.

Kennard, M., Pusey, B. & Arthington, A. (2001). Trophic ecology of freshwater fishes in Australia. Summary report, CRC for Freshwater Ecology Scoping Study SCD6. CRC for Freshwater Ecology, Griffth University, Brisbane, Australia.

Larson, H.K. & Martin, K.C. 1990. Freshwater Fishes of the Northern Territory. Northern Territory Museum of Arts and Sciences, Darwin. 102pp.

Lintermans, M. 2007. Fishes of the Murray-Darling Basin: an introductory guide. Murray-Darling Basin Commission, Canberra.

McDowall, R. M. (ed.) 1996. Freshwater Fishes of South-Eastern Australia, 2nd ed. Reed Books, Sydney. 247pp.

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.

Merrick, J.R. 2006. Australasian freshwater fish faunas: diversity, interrelationships, radiations and conservation. Pp. 195 – 224. In Merrick, J.R., Archer, M., Hickey, G.M. and Lee, M.S.Y. (eds). Evolution and Biogeography of Australasian Vertebrates. Auscipub Pty. Ltd., Sydney. 942 pp.

Midgley, S. H., Midgley, M., & Rowland, S. J. 1991. Fishes of the Bulloo-Bancannia drainage division. Memoirs of the Queensland Museum. 30(3): 505-508.

Merrick, J. R. and Schmida, G. E. 1984. Australian freshwater fishes: biology and management. Adelaide, Griffen Press, 409pp.

Morgan, D., Allen, G., Pusey, B. & Burrows, D. 2011. Freshwater fishes of the Kimberley region, north-western Australia. Zootaxa 2816: 1–64.

Murray-Darling Basin Commission. 2004. Native Fish Strategy for the Murray-Darling Basin 2003-2013, Canberra, MDBC Publication No. 25/04. http://publications.mdbc.gov.au/download/native_fish_strategy_for_m_d_basin_2003-13.pdf

Pusey, B.J., Kennard, M.J. & Arthington, A.H. 2004. Freshwater Fishes of North-eastern Australia. CSIRO Publishing, Melbourne. 645 pp.

Unmack, P. J. 1995. Desert fishes down under. Proceedings of the Desert Fishes Council 1994. 26: 71-95.

Unmack, P.J. 2001. Biogeography of Australian freshwater fishes. Journal of Biogeography 28: 1053–1089.


Author: Dianne J. Bray