The adult Rock Beauty angelfish's overall body color can be described as yellow in the facial region of the body with blue towards the tail end of the fish. Its tail, however, will retain the yellow coloration. Their pectoral fins and ventral fins are also yellow but their lips and the edges of their dorsal fins and anal fins are dark blue. An adult Rock Beauthy angelfish can measure up to 10 inches (25 cm).
The Rock Beauty Angelfish feeds primarily on sponges. It may also feed on small amounts of tunicates, jellyfish, and corals, as well as plankton and algae. In home aquariums, aquarists have had limited success in providing the Rock Beauty Angelfish a diet of meaty and algae-based foods. Without some amount of sponge in the diet, however, most Rock Beauty Angelfish perish in captivity.
The adults are found in pairs year round, perhaps suggesting a long-term monogamous bond. The pairs reproduce by rising up in the water, bringing their bellies close together, and releasing clouds of sperm and eggs. The female can release anywhere from 25 to 75 thousand eggs each evening and as many as ten million eggs during each spawning cycle. The eggs are transparent, buoyant, and pelagic, floating in the water column. They hatch after 15 to 20 hours into larvae that lack effective eyes, fins, or even a gut. The large yolk sac is absorbed after 48 hours, during which time the larvae develop normal characteristics of free-swimming fish. Larvae are found in the water column and feed on plankton. The larvae grow rapidly and about 3-4 weeks after hatching the 15-20mm long juvenile settles on the bottom.
In the aquarium
The Rock Beauty Angelfish is considered to be a difficult fish to keep in captivity; it is ill-suited for all but the most experienced aquarists. They are highly specialized feeders that will likely perish without some marine-sponge formulation in their daily diet. They are an aggressive species. Most aquarists recommend a minimum tank size of 100 gallons. Young Rock Beauty Angelfish feed in part, on the slime of other fish and will persistently chase their tankmates and nip at them. It is not a reef safe fish, and larger specimens may nip at or consume corals, particularly stony or soft ones, and ornamental invertebrates.