The Emperor Angelfish, Pomacanthus imperator, has three distinct stages of life that, together, create one single dynamic angelfish species. These stages are the juvenile stage, intermediate stage, and adult stage. Each stage of life for the Emperor Angel is unique. This transformation best seen in the Emperor Angel's coloration and patterning. Below will be short descriptions of each formative stage. This entire process can span the time of up to two years.
Juvenile. Juvenile Emperor Angelfish exhibit white circles across a blue/black body. Each white circle is inside one larger spanning out from the dorsal fin region. At this stage, the Juvenile Emperor Angelfish's tail is clear. They will be in this stage until they are about four inches in length.
Intermediate. Intermediate Emperor Angelfish exhibit the same similar white circle pattern as the Juvenile Emperor but with lateral yellow lines crossing through the white circles. Eventually, the white circles begin to disappear making room for the beautiful yellow coloring the Emperor Angelfish is so known for. The tail begins to transition from clear to the classic yellow. Once the Emperor Angelfish reaches about six inches, it will usually reach its final coloration form.
Adult. The adult Emperor Angelfish is commonly referred to as the Imperator Angelfish. With its beautiful blue body covered with bright yellow horizontal stripes, it makes a captivating addition to any tank. The changing angelfish will vary in coloration and pattern as it transforms from juvenile to the adult coloration. It grows up to 16 inches and needs to be kept in a tank not less than 150 gallons. The adult Emperor Angelfish needs plenty of live rocks for hiding and grazing, that is why make sure to decorate the aquarium cleverly. It also requires extensive rockwork and deep caves to feel secure. The adult Emperor Angelfish may found nipping at stony and soft corals, clam mantles, but doesn't disturb other small polyped stony corals. It should be fed a diet of Spirulina, marine algae, high-quality angelfish preparations, mysis or frozen shrimp, and other meaty items. The adult Emperor Angelfish thrives well in a temperature range of 72-78 degrees Fahrenheit and pH of 8.1-8.4. It is slow to accept captivity and very shy in nature. The adult Emperor Angelfish is susceptible to a variety of parasites and proper quarantine procedures are then recommended. It is not considered reef safe though some specimens have been reported to live peacefully without harassing small-polyped stony corals.