In the western parts of its range, in Ecuador and Peru they develop striking red or orange colouration on the lower jaw, the head and the forward portion of the belly while Brazilian specimens are more of an overall grey or blue or green colouration.

[1] The saddle cichlid is a habitat generalist which shows a preference for slow-moving or still water with complex substrates consisting of submerged tree roots, branches, leaf litter and other objects.

It is most commonly observed in the quieter tributaries instead of the main river channels and has also been recorded at localities with a dense growth of aquatic plants.

[2] They are omnivorous, especially in captivity, but wild fish have diet dominated by invertebrates, such as insects, and small fish, as well as some vegetable matter[4] It is a highly territorial species which lives in pairs.

A. tetramerus and its closely related taxa have been found to be a sister taxa to the genus Cichlasoma and this has suggested that Aequidens is a nomen dubium due to paraphyly and that all but two species should be placed in the genus Cichlasome while two species should be placed in Krobia.