The southern mud oyster or native flat oyster, Ostrea angasi, is endemic to southern Australia, ranging from Western Australia to southeast New South Wales and around Tasmania.
This species is found in sheltered, silty or sand-bottomed estuaries at depths between 1 and 30 m.
Flat oysters, like all other oyster species, are filter feeders, feeding on, and taking in anything small enough to be filtered in their gills. This may include plankton, microalgae or inorganic material.
The oyster industry in southern Australia has started farming O. angasi, after supplies of wild-caught individuals were exhausted due to overfishing.