The radjah shelduck inhabits brackish and saltwater lakes, shallow freshwater lakes and mangrove flats. It feeds on insects, crustaceans, molluscs, worms, small fish and sometimes sedges. The species lives in lone pairs or in flocks of 6–8 individuals. In the dry season, flocks of 20–60 individuals can be seen (on rare occasions even more than 200). Incubation of 7–10 eggs in tree or ground hollows lasts 28–33 days.
Status according to Red List:Least concern (LC)