Summary Indigenous people demonstrably lived along rivers and around lakes and wetlands of Australia's Murray-Darling Basin in pre-European times. Waterways were, and continue to be, of major significance to the society and culture of Aboriginal peoples throughout Australia. Historically, they exploited most of the fauna – from mussels and crayfish, to fish and birds – and either ate, or used for other purposes, many species of aquatic plants. Such practices placed them in the role of environmental modifiers, a role played by all human groups from both past and present. They built sophisticated fish traps, cut gaps in river banks to allow fish to move on to floodplains, and there is evidence that they practised a form of fish culture by creating small impoundments in which small fish could live and grow in normally ephemeral tributary streams away from predatory larger fish. Knowledge of the numbers of Aboriginal people inhabiting the riverine regions of the Murray-Darling Basin are sketchy, but at times large groups congregated for cultural reasons, facilitating fishing with extensively engineered fish traps, such as that at Brewarrina, on the Barwon River in New South Wales. At other times, densities may have been about 0.5 person per river kilometre, although this was certainly not evenly distributed and the calculation postdated deaths from smallpox. From archaeological and anthropological evidence, aquatic fauna and flora would have constituted between about 30% and 100% of the diets of Indigenous people historically, depending on season and location. As such, Indigenous people were very much a part of the ecology of aquatic ecosystems and their effects may have been profound. Despite this, their role in influencing these ecosystems has largely been ignored by contemporary freshwater ecologists and managers. Current management practices do not seem to have considered the loss of this component of riverine ecosystems, and there is little debate about how the historical part that Indigenous people played in shaping these systems and their biota might be incorporated into management generally.