Steatocranus casuarius is a small, specialized rheophilic cichlid adapted to fast-flowing waters. Its body is elongated and slightly compressed, usually gray to brown with subtle patterning that provides excellent camouflage among rocks.

A notable feature is the forehead hump on males, which becomes more prominent with age and dominance. Adult size is modest, reaching 6–8 cm, making them ideal for smaller Tanganyika setups or biotope tanks.

Males tend to be larger and more robust than females, with longer fins and a more pronounced forehead.