The two types of angelfish are freshwater and marine. There are three species of angelfish found in freshwater that have been bred by aquarists to create new strains. Approximately 89 species of marine angelfish live in shallow reefs in the tropical Atlantic, Indian, and western Pacific Oceans. The freshwater types of angelfish form the genus Pterophyllum, and the marine angels are from the Pomacanthidae family. The markings, colors, and habitat of the different types of angelfish vary widely between species.
The most common types of angelfish found in home aquariums are freshwater angels from the Cichlidae family. The three known species are P. altum, P. leopoldi, and P. scalare. This trio originates from tropical South America and is found in the Orinoco, Essequibo, and Amazon River basins. These angels have flat bodies, triangular anal and dorsal fins, and distinctive dark stripes that provide camouflage among the vegetation they typically live in.
P. scalare is the most widely available species of angelfish found in freshwater. Originally described by M.H.C. Lichtenstein in 1823, this angel prefers swamps, dense vegetation, and clear or silty water. The water of its native habitat ranges between 75 and 86 degrees Fahrenheit (24 to 30 degrees Celsius) and has a pH of six to eight. These freshwater types of angels are ambush predators that target smaller fish and macroinvertebrates like larvae.
As these freshwater types of angelfish can grow tall, they often require a large tank when kept in captivity. A 50-gallon tank that is at least 18 inches (47 centimeters) deep would be sufficient for 12 to 15 angels. As these angels reach full size, the number in the tank should be reduced by half. Freshwater angelfish do best alone or in groups of more than three. Breeding pairs are monogamous and will spawn on flat surfaces in the tank like broad leaves or the glass aquarium wall. In captivity, angels are typically fed a diet of flake food and dried blood worms.
Aquarists have created new strains of freshwater angels by cross-breeding the three known species. Some strains are stripeless with dramatic coloring, while others have unique scales or fins. For example, the gold strain has a light golden body and a dark yellow head but lacks the red eyes and stripes typical of wild angels. The halfback had a silver upper body with dark stripes but a black rear and tail. The leopard has a body covered with dark brown spots.
Other types of angelfish are marine and live in tropical ocean waters among the shallow reefs. These angels often boast bright coloring and markings and have smaller fins with extensions that trail behind them in the water like streamers. Smaller species can be found in home aquariums, but the larger varieties can reach up to 24 inches (60 cm) in length and are therefore too big for most hobbyists to maintain.
These marine types of angelfish are believed to be curious and may approach scuba divers in the water. They are generally diurnal and hide within the crevices of the reefs at night. When these types of angelfish spawn, they release thousands of eggs into the water that float among the plankton until they hatch.
Marine angels typically have an ornate appearance that can change as the fish matures. For example, a male ornate angelfish will have a body decorated with thick, dark bands when immature. Once mature, the ornate will develop additional orange bands on its flanks. The French angelfish has black scales that are rimmed in yellow, a white chine, and eyes highlighted in blue. Such variety of color attracts many aquarists to these types of angelfish.