The adult rock beauty is mostly yellow, turning blue toward the tail. The tail itself is yellow. The pectoral fins and ventral fins are yellow, and the lips and the edges of their dorsal fins and anal fins are dark blue. The adult measures up to 10 inches (25 cm).
The rock beauty feeds primarily on sponges. It may also eat tunicates, jellyfish, and corals, as well as plankton and algae. In home aquaria, keepers have had limited success with diets of meat- and algae-based fish foods. The fish requires sponges to survive.
The adults stay 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 produces 25,000 to 75,000 eggs per day, and up to 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 begin to develop normal characteristics of free-swimming juveniles. They feed on plankton for 3 to 4 weeks, reaching 1.5 to 2 centimeters in length, and then settle on the bottom as juveniles.
- Pyle, R., et al. 2010. Holacanthus tricolor. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. Downloaded on 05 June 2013.