Rock Beauty Angel
Minimum Tank Size: 125 gallons
Care Level: Difficult
Reef Compatible: With Caution
Water Conditions: 72-78° F, dKH 8-12, pH 8.1-8.4, sg 1.020-1.025
Max. Size: 8"
Color Form: Black, Yellow
The adorable juveniles are all yellow, but with a black spot trimmed in bright blue on the upper back. This spot is likely imitating the similarly colored eye, which helps to confuse predators. As they mature the black spot expands until it covers most of the body. The coloring of these juveniles is very similar to the Threespot Damselfish Stegastes planifrons, which occurs across the same range. However the damsel has a more elongated body while the angelfish is rounder, and the angel lacks another small spot on the top of the caudal fin base.
The coloration is quite striking, but along with these good looks are additional benefits for the Rock Beauty. Their appearance allows them to blend in with the rocks and rubble of the coral reefs where they live. They stay very close to the reef structure for their entire lives and become quite territorial as they defend their home. Thus it is commonly called the Rock Beauty, but is also known as the Yellow Nanny Angelfish, Corn Sugar Angelfish, and Coshubba. Juveniles are commonly found among Millipora Fire Corals, which are a "stinging coral" that can cause a burning sensation if touched. Divers and snorkelers need to exercise caution and wear gloves when anywhere near these corals.
These angelfish can be a challenge to keep due to their nutritional needs as adults, and are really only suited for advanced aquarists. Although juveniles are easier to feed, eating more algal type foods, adults are very dependent on sponge material for nutrition. Because they are a smaller size one would think a smaller tank would be fine, but the dietary needs of this angelfish dictate a larger tank. They are also timid fish that needs a calm environment and plenty of caves and crevices within rockwork for places to hide. They need a mature tank of at least 100 gallons that has live rock with lots of encrusting sponge material and plenty of algae growth to help them adjust and to maintain them. A varied diet that includes sponge material specifically designed for marine angelfish has been suggested as well to make sure they get their needed nutrients.
They can be kept in a fish community, but juveniles will often be seen picking at other fish. They are not removing parasites as some of their Holacanthus cousins are known to do, but are actually nipping at the slime that the fish are producing. This behavior has been mistaken as aggressive behavior, but it is more of a nutritional need than a desire to dominate other fish. However they have been known to actually terrorize Blue Chromis Chromis cyanea with this behavior, due to the large amount of body slime these damsels produce. In the wild juveniles are seen nipping at the copious amounts of mucous that the Goldentail Moray Eel Gymnothorax miliaris produces.
Their territorial nature puts them at odds with any other angelfish in an aquarium. Housing them with fish that are larger or smaller is the best choice. Adults will pick on similar sized fish such as wrasses, batfish, butterflyfish and sweetlips, but smaller benthic fish are ignored in larger aquariums. They are not considered reef safe as corals will be nipped at, but invertebrates such as cleaner shrimp, snails, and crabs are generally left alone.