Fish
Emperor Angelfish
Pomacanthus imperator · also called imperator angelfish
Gliding along a reef wall in bold yellow and blue stripes, an adult emperor angelfish looks nothing like the dark blue, white-ringed juvenile it once was, one of the most dramatic colour transformations found among reef fish.
Overview
The emperor angelfish, Pomacanthus imperator, is native to ocean and coastal reef habitat across the Indo-Pacific region. Its striking change in appearance with age, sponge-focused diet, and defensive gill-cover spine make it one of the most recognisable and visually remarkable marine angelfish found anywhere.
Two fish in one
The emperor angelfish passes through two almost unrecognisable looks in a single life, a dark blue, white-ringed youngster giving way to a stripe-patterned adult so different that early naturalists treated the stages as separate species.
Status
Least Concern, remaining widespread across suitable reef habitat throughout the Indo-Pacific region.
Emperor Angelfish: common questions
Why do young and adult emperor angelfish look so different?
Juveniles are dark blue with concentric white rings and curved lines, while adults develop bold yellow and blue stripes with a dark mask, a complete change that can make the two stages look like separate species.
What does the emperor angelfish eat?
It is an omnivore that feeds mainly on sponges and tunicates, supplemented by algae and other small reef organisms.
What is the spine on an emperor angelfish for?
A sharp spine on the lower edge of its gill cover is a defensive feature shared across marine angelfish, and it is one way to tell angelfish from similar-looking butterflyfish.
Where is the emperor angelfish found?
It is native to ocean and coastal reef habitat across the Indo-Pacific region.