It is found from Maputo Bay in Mozambique southwards along the coast of South Africa as far as Knysna in the Western Cape.

[1] The old woman angelfish is found along shorelines and on rocky reefs at depths between 5 and 30 m (16 and 98 ft).

[1] The adults live in small groups close to the coast where they feed on algae and benthic invertebrates.

[1] The old woman angelfish was first formally described in 1908 as Holacanthus rhomboides by the Scots ichthyologist John Dow Fisher Gilchrist (1866–1926) and his South African colleague William Wardlaw Thompson (died 1917) with the type locality given as KwaZulu-Natal.

The specific name of this species, rhomboides means “rhombus-like”, possibly a reference to its deep, almost quadrangular body.