Common name for a species of marine reef-fish, with the scientific name
Pomacanthus imperator. Juveniles look nothing like the adults and live separately from them, usually inhabiting outer lagoon patches of the marine reefs, in part due to the fact that adults mate at the surface in order to allow their fertilized eggs to be taken away on currents, ensuring greater dispersion, as well as preventing egg-eating predators from spotting the eggs. Immature fish (fig.) are dark blue to black, with a pattern of white, vivid blue and yellow lines, that form concentric rings toward the centre rear of the body and become circular spots on the dorsal and anal fins. In the wild, the body colour of adults is yellow with blue stripes, a white snout and a black eye-mask, that is lined with pale blue, while the area around the gills and below the mouth is black, while the anal fin and pelvic fins are black with vivid blue lines, and the tail is bright yellow. It takes up to two and a half years for Emperor Angelfish to acquire their adult colouring, though the transition may not fully occur in captivity. They can grow up to 4 centimeters tin length. Emperor Angelfish live at depths of up to 100 meters and are omnivorous, although their primary diet consists of sponges and algae. When they are disturbed or feel threatened, adults are said to produce a low-frequency knocking sound. In Thai, this species is known as pla sin samut chakrapat (ปลาสินสมุทรจักรพรรดิ).