The word angelfish is a general term that refers to many different kinds of fish. Typically, angelfish have thin bodies that are flattened laterally. They tend to have elongated dorsal, anal, and pelvic fins, and display a wide variety of colors, making them popular aquarium species. The association of these fish with angels may be due to the fins resembling wings.
All angelfish belong to the taxonomic order Perciformes. This varied group contains two families of angelfish. The so-called true angelfish belong to the family Pomacanthidae. Butterfly fish, another group of angelfish species, belong to the family Chaetodontidae. True angelfish are distinct from butterfly fish by the presence of a spine near the bottom margin of the operculum, the outer gill covering. There are eight scientific genera of angelfish found worldwide.
All species of angelfish are tropical, but surprisingly, some species inhabit freshwater while others prefer salt water. Angelfish are typically small, reaching only a few centimeters in length. However, some species are much larger, growing up to 2 ft (61 cm) in length. Most angelfish feed on small aquatic invertebrates. Several species are bred and cultivated as aquarium pets, others are taken from coral reefs and sold to enthusiasts.
Angelfish varieties have colorful names that reflect their appearance. Examples include Flame, Coral Beauty, Lemon Peel, and Dwarf Angel. Members of the shark genus Squatina are called angelfish because their pectoral fins resemble wings. These animals are not closely related to the angelfish kept as pets in aquariums.