Pomacanthus semicirculatus, also known as the semicircled angelfish, Koran angelfish, blue angelfish, zebra angelfish or half-circled angelfish, is a species of ray-finned fish, a marine angelfish, in the family Pomacanthidae. It is found in the Indo-West Pacific Ocean. It occasionally makes its way into the aquarium trade.

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 about 86 species. They should not be confused with the freshwater angelfish, tropical cichlids of the Amazon Basin.