[1] It is polymorphic and can have white or gold-orange edging to the tail and dorsal fins.

It has historically been confused with two other species that always have narrow, clearly defined white edging, the more southerly distributed A. stalsbergi (often considered the "true" green terror) and the more northerly A.

[2][3] Males of A. rivulatus grow larger than females and may reach lengths of up to 30 cm (12 in).

Adult males develop a pronounced forehead hump, composed of fatty tissue.

A. rivulatus is a popular fish in the aquarium trade and is noted for its hardiness, as well as its aesthetic appeal.