Pygocentrus spp. are not exclusive carnivores and are more accurately described as opportunistic generalists.
The natural diet consists of live fishes plus aquatic invertebrates, insects, nuts, seeds, and fruits. Each jaw contains a single row of sharp, pointed, triangular teeth, which are used like blades to puncture, tear, chop, and crush.
They sometimes attack sick or dying fishes, scavenge carcasses, or bite chunks from the fins of larger species, but assaults on live animals entering the water are very rare and mostly relate to accidental biting or cases in which numbers of fish have become trapped in small pools during dry periods.
In the aquarium juveniles can be offered chironomid larvae (bloodworm), small earthworms, chopped prawn, and suchlike, while adults will accept strips of fish flesh, whole prawns, mussels, live river shrimp, larger earthworms, etc.
This species should not be fed mammalian or avian meat since some of the lipids contained in these cannot be properly metabolised by the fish and may cause excess fat deposits and even organ degeneration. Similarly, there is no benefit in the use of ‘feeder’ fish such as livebearers or small goldfish, which carry with them the risk of parasite or disease introduction and tend not have a high nutritional value unless properly conditioned beforehand.