The emperor angelfish, Pomacanthus imperator, is a species of marine angelfish

Marine angelfish

Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific oceans. The family contains seven genera and approximately 86 species...

. It is a reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

-associated fish, native to the Indian

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

s, from the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

 to Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 and the Austral Islands

Austral Islands

The Austral Islands are the southernmost group of islands in French Polynesia, an overseas collectivity of France in the South Pacific. Geographically, they consist of two separate archipelagos, namely in the northwest the Tubuai Islands consisting of the Îles Maria, Rimatara, Rurutu, Tubuai...

.

Juveniles are dark blue with electric blue and white rings; adults have yellow and blue stripes, with black around the eyes. It takes about 24 to 30 months for an emperor angelfish to acquire its adult colouring. They grow to 40 cm (15.75 in) in length.
Juvenile to adult transition may not fully occur in an aquarium.