Pomacanthus rhomboides

Lore & Background

The old woman angelfish was first formally described in 1908 as Holacanthus rhomboides by the Scots ichthyologist John Dow Fisher Gilchrist and his South African colleague William Wardlaw Thompson, with the type locality given as KwaZulu-Natal. The species is placed by some authorities in the subgenus Acanthochaetodon. The specific name rhomboides means 'rhombus-like', possibly a reference to its deep, almost quadrangular body.

Adults are bronze brown on the anterior two thirds of their bodies with the posterior third being pale bluish grey. Juveniles resemble those of other species in the genus and are more colourful, mainly black with thin, wavy blue and white lines. The dorsal fin contains 11-13 spines and 22-25 soft rays while the anal fin contains 3 spines and 21-23 soft rays. This species attains a maximum total length of 46 centimetres.

The old woman angelfish is found from Maputo Bay in Mozambique southwards along the coast of South Africa as far as Knysna in the Western Cape. It is found along shorelines and on rocky reefs at depths between 5 and 30 m. Juveniles are found in shallow tidal pools. Adults live in small groups close to the coast where they feed on algae and benthic invertebrates, and will occasionally swim near the surface to feed on plankton.

Reader's Guide

The old woman angelfish has a range which does not overlap with the main areas of Africa's coast where fish are collected for the aquarium trade and is subsequently extremely rare in that trade. Its distribution is limited to the western Indian Ocean, specifically from Maputo Bay in Mozambique southwards along the coast of South Africa to Knysna in the Western Cape. The species is notable for being possibly the least colourful adult in the genus Pomacanthus, with a bronze brown anterior and pale bluish grey posterior. Juveniles, however, are more colourful with black bodies and thin blue and white lines. The fish inhabits shorelines and rocky reefs at depths of 5 to 30 m, with juveniles in tidal pools. Adults feed on algae, benthic invertebrates, and occasionally plankton near the surface. Its scientific description was published in 1908 by Gilchrist and Thompson, and some authorities place it in the subgenus Acanthochaetodon. The specific name rhomboides refers to its deep, almost quadrangular body shape.

Did You Know?

• Its specific name rhomboides means 'rhombus-like', possibly referring to its deep, almost quadrangular body.
• Adults are bronze brown on the anterior two thirds and pale bluish grey on the posterior third.
• This species is extremely rare in the aquarium trade because its range does not overlap with main collection areas.