The Emperor Angelfish (Pomacanthus imperator) is also known as Imperial Angelfish and Imperator Angelfish. The name is commonly shortened to Emperor Angel / Imperial Angel / Imperator Angel in everyday speech.  

Pomacanthus imperator has not been evaluated for the IUCN Red List of Threatened Species.

Geographical distribution, habitat and habits

The Emperor Angelfish lives in the Indo-Pacific. Its range stretches from East Africa and the Red Sea to Hawaii, the Equatorial Islands, and the Tuamotu Archipelago of French Polynesia. Northwards, the range proceeds up to southern Japan and the Ogasawara Islands. Southwards, you can find this species down to Australia's Great Barrier Reef, New Caledonia and the Austral Islands of French Polynesia. Emperor Angelfish has not been encountered in the waters around Easter Island, Rapa Island or the Marquesan Islands. 

The Emperor Angelfish is a reef-associated species. Juveniles prefer to stay hidden under ledges or inside holes of outer lagoon patch reefs or semi-protected areas of exposed channels and outer reef flats. As they grow older, they move to holes located at reef fronts and in surge cannels. Large adult specimens are found in areas with prolific algae growth on clear lagoon, channel, or seaward reefs. This fish typically seek shelter in caves and under ledges even as an adult. The depth range for this species is 1-100 meters / 3-330 feet.

Size and appearance

The largest scientifically measured Emperor Angelfish was 40.0 cm / 15.7 in.

The juvenile fish has a bluish black body adorned with concentric white circles. The dorsal fin margin is also white. Juveniles will change into their adult colouration over the size range 8-12 cm / 3-5 in.

The adult fish is blue and decorated with close-set horizontal yellow stripes on the sides and the adjoining dorsal and anal fins. The caudal fin is of a striking yellow to orange shade. The eye is enclosed by a black vertical bar with blue edging. The pectoral fin base is black while the snout is white.

Emperor Angelfish care

The Emperor Angelfish is considered moderately difficult to keep and is not recommended for novice marine aquarists. It should only be placed in mature and stable aquariums with ideal water conditions. 

It is not advisable to keep an Emperor Angelfish in an aquarium smaller than 100 gallons / 375 litres. As the Emperor Angelfish grows bigger, you will probably need a 200 gallon / 750 litre aquarium if you want your fish to thrive. The aquarium should always include plenty of live rock for grazing when housing this species. It is also important to create a lot of suitable hiding spots, such as ledges and caves.

The Emperor Angel is considered reef compatible with caution. It will nip at stony corals, soft corals and clam mantles, but tends to leave somewhat noxious soft corals alone. If you want to keep stony corals, ideally go for variants with small polyps.

The Emperor Angel is a semi-aggressive species. It is highly territorial towards members of its own species and angelfish from other species. It is sometimes possible to house several angels together by picking fish of very different sizes and introduce the smallest specimens first.  

The recommended water temperature is 72-78º F / 22-25.5º C. Keep the specific gravity at 1.022-1.025 and the pH-value between 8.2 and 8.4.

Feeding Emperor Angelfish

In the wild, the Emperor Angelfish feeds primarily on sponges and other encrusting organisms, but it is also fond of tunicates, other animals, algae, and vascular plants. Young adult specimens can work as cleaners and remove parasites from larger fish.

You need to mimic this omnivore diet in the aquarium, but you don’t have to feed it only sponges and tunicates because it will usually adapt well to a diet consisting of various meaty foods such as shrimps. It can normally be trained to eat fresh, frozen, formula and dry food in addition to live food. Supplement the meaty foods with spirulina and marine algae and encourage natural algae growth in the aquarium. Serving a high-quality angelfish preparation is recommended.  

An improper diet, e.g. one that is not vitamin rich enough, can dampen the colours of adult fish and young specimens can fail to carry out the proper colour transition from juveniles to adults.

Breeding Emperor Angelfish

The Emperor Angelfish is an egg-laying species that will scatter the eggs. It forms pair and they are believed to be life long (more research is needed). The female will release her eggs depending on tidal action, the lunar cycle and light stimuli.

Marine Angelfish Articles:

African Flameback Angelfish – Centropyge acanthops
Asfur Angelfish – Pomacanthus asfur
Bicolor Angelfish – Centropyge bicolor
Blueface Angelfish – Pomacanthus xanthometopon
Cherub Angelfish – Centropyge argi
Coral Beauty – Centropyge bispinosa
Flame Angelfish – Centropyge loricula
French Angelfish – Pomacanthus paru
Herald's Angelfish – Centropyge heraldi
Koran Angelfish – Pomacanthus semicirculatus
Lamarck's Angelfish – Genicanthus lamarack
Potter's Angelfish – Centropyge potteri
Queen Angelfish – Holacanthus ciliaris
Regal Angelfish – Pygoplites diacanthus
Rock Beauty Angelfish – Holacanthus tricolor
Rusty Angelfish – Centropyge ferrugata
Watanabe's Angelfish – Genicanthus watanabei