The world's fish fauna is dominated by two groups, Ostariophysi (9622 species) and Acanthopterygii (16207 species), which combined account for about 81 per cent of all fishes.  Most freshwater fish faunas are dominated by ostariophysans, consisting of minnows (Cypriniformes), characins (Characiformes) and catfishes (Siluriformes).  In contrast, the worlds marine habitats are dominated by acanthopterygian fishes.  The freshwater fish fauna of the Australian continent (which includes New Guinea) is exceptional in being dominated by acanthopterygian fishes rather than ostariophysans.  Indeed, Australia has the only freshwater representatives for many acanthopterygian families. This makes the continental fish fauna unlike any other apart from the island of Madagascar.  While Australia’s extraordinary mammal fauna receives a lot of attention, our fish fauna is no less distinctive.  While most Australian freshwater fishes ultimately have marine origins, most families have been present in Australian freshwaters for at least 40-80 million years.  In this presentation I will review the phylogenetic information that examines the number of marine – freshwater transitions for various Australian freshwater groups and provide approximate estimates for the timing of these invasions.