The adult imperator Angelfish, also called the Emperor Angelfish, has a bold, blue body covered with bright yellow horizontal stripes culminating in a bright yellow to orange caudal fin. A striking blue-black mask covers the eyes and a similarly-colored vertical band extends from the pectoral fin two-thirds of the way up the body. This band is highlighted in a sapphire-blue in front, and bright yellow, caudally. The mouth is white.
The juvenile is black with circular white and blue stripes starting at the tail. Although sought after for its colors, in captivity, the adult coloration may not be as striking or brilliant, and the color transition from juvenile to adult, may not be complete. Supplementing the diet with vitamins and color-enhancing foods may help.
The Imperator Angelfish requires a 300 litre or larger tank with live rock for grazing and hiding. They also require extensive rockwork and deep caves to feel secure. It will nip at stony and soft corals (sessile invertebrates) and clam mantles, but may be kept with small-polyped stony corals and somewhat noxious soft corals.
It should be fed a diet of Spirulina, marine algae, high-quality angelfish preparations, mysis or frozen shrimp, and other meaty items.