1. There are around 100 different species of angelfish that inhabit the waters of the southern hemisphere. There are two main types of angelfish, those that live in the freshwater rivers in South America (freshwater angelfish) and those angelfish that inhabit the salty ocean waters (marine angelfish).

2. Pterophyllum is a small genus of freshwater fish from the family Cichlidae known to most aquarists as "angelfish". All Pterophyllum species originate from the Amazon Basin, Orinoco Basin and various rivers in the Guiana Shield in tropical South America. The three species of Pterophyllum are unusually shaped for cichlids being greatly laterally compressed, with round bodies and elongated triangular dorsal and anal fins. This body shape allows them to hide among roots and plants, often on a vertical surface. Naturally occurring angelfish are frequently striped longitudinally, colouration which provides additional camouflage. Angelfish are ambush predators and prey on small fish and macroinvertebrates. All Pterophyllum species form monogamous pairs. Eggs are generally laid on a submerged log or a flattened leaf. As is the case for other cichlids, brood care is highly developed.

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