Freshwater fish of Australia are limited to approximately 280 species, even though the Australian continent is larger than the contiguous United States.
[1] The small scale of species found in Australian inland waters is in some part due to the dry conditions of the continent.
Due to the illegal introduction of carp (Cyprinus carpio), Cyprinidae is now present in a destructive form in Australia.
The Galaxiidae have become significant in scale in Australia, most of the world's Galaxias species are found in the continent and neighbouring New Zealand.
The majority of Australian freshwater fishes are poorly understood and are under threat due to human activities such clearing of riparian vegetation and siltation associated with agricultural practices, snag removal, overfishing, river regulation through dams and weirs, introduced fish and diseases.