Additional information (Wiki): A. ocellatus have been reported to grow into a length of 34 cm (approximately 15 in) and a mass of 1.6 kg (2.6 lb).

 The wild caught forms of the species are typically darkly coloured with orange ringed-spots or ocelli on the caudal peduncle and on the dorsal fin. It has been suggested that these ocelli function to limit fin-nipping by piranha (Serrasalmus spp.) which co-occur with A. ocellatus in its natural environment. The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics.

 Juvenile A. ocellatus have a different colouration from adults and are striped with white and orange wavy bands and have spotted heads.