The stomach contents of 257 specimens of Epinephelus marginatus (197-920 mm TL) obtained between February 1999 and December 2003 in Santa Catarina State (South Brazil) were investigated in order to analyse their diet composition and understand the feeding strategy and interspecific diet overlap. E. marginatus from south Brazil fed mainly on brachyuran crustaceans, followed respectively by teleost fish and cephalopods. In ontogenetic terms the importance of these groups remains practically the same and the feeding strategy also did not show significant shifts. A generalist strategy with heterogeneous feeding is present in all four size classes and the increase of nutritional requirements during the life cycle is satisfied by predating on larger prey instead of a greater number of preys. Changes in the relative importance of the main prey species and brachyuran prey size-range appear to be an important mechanism to prevent dietary niche overlap in E. marginatus from south Brazil.