The geelbeck croaker was first formally described as Otolithus aequidens in 1830 by the French zoologist Georges Cuvier with its type locality given as False Bay in the Western Cape.

[2] The geelbeck croaker is found in the southwestern Indian Ocean from Cape Agulhas east along the South African coast and north as far as Pinda in the Zambezia Province of Mozambique.

[1] The adults gather in schools offshore over sandy bottom, on rocky reefs, and close to wrecks and pinnacles, at depths between 15 and 200 m (49 and 656 ft)> the juveniles are occasionally found in estuaries.

[8] Geelbeck croakers are nocturnal piscivores, the adults feed on pelagic fish[2] like pilchard (Sardinops sagax)., as well as Japanese anchovy (Engraulis japonicus), and Cape horse mackerel (Trachurus capensis).

The pelagic eggs and larvae drift in a southwesterly direction following the inshore peripheral waters of the Agulhas Current.