[2] In tropical South America, where the species naturally resides, A. ocellatus specimens are often found for sale as a food fish in the local markets.

[2] The wild-caught forms of the species are typically darkly coloured with yellow-ringed spots or ocelli on the caudal peduncle and on the dorsal fin.

[11] Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.

[2][3] In its natural environment, the species typically occurs in slow-moving white-water habitats, and has been observed sheltering under submerged branches.

[6] Feral populations also occur in China,[12] northern Australia,[13] and Florida, USA[14] as a byproduct of the ornamental fish trade.

[17] A. ocellatus fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild is scarce.

Most fish eaten by A. ocellatus in the wild are relatively sedentary catfish, including Bunocephalus, Rineloricaria, and Ochmacanthus species.

[10] The species uses a suction mechanism to capture prey,[18] and has been reported to exhibit "lying-on-side" death mimicry in a similar fashion to Parachromis friedrichsthalii and Nimbochromis livingstonii.