Saltwater aquariums can be used to house a wide range of unusual and beautiful fish species. One type, the blue angelfish, is a colorful addition to the aquarium, with shiny blue and gold markings on its face and fins. The blue angelfish is relatively large, growing up to 18 inches in length (about 45 cm) and is moderately easy to care for. This species has some unusual habits that make it best kept only under certain conditions.
When blue angelfish are young, their bodies are dark, with several vertical bright blue stripes on their sides. As they get older, their color changes to a golden yellow, and the bright blue stripes disappear. Mature blue angelfish have blue accents on their fins, above their eyes, and along their gills. These fish do not have any markings or other indicators to show if the fish is a male or a female, and even people that are very experienced with these fish usually cannot distinguish between the sexes.
Blue angelfish should be kept in a large aquarium, at least 100 gallons (about 378 liters), though a larger tank is preferred. These fish are bottom dwellers in their natural habitat, staying among the rocks and coral at depths of 6 to 300 feet (about 2 to 92 meters). They come from the western part of the Atlantic Ocean, mainly from along the coasts of Bermuda and Mexico. Usually, they are out swimming during daylight hours, seeking out food, but at night they hide in order to sleep. It is important that they have plenty of places to hide in an aquarium so that they feel safe.
The natural food for a blue angelfish consists mainly of sponges, but they will eat coral, sea squirts and algae as well. These fish are best kept in an aquarium free of live coral and sponges, since they will nip at these, killing or damaging them. When creating an environment for a blue angelfish, rocks and other non-living items are a better choice than coral. Blue angelfish are somewhat aggressive, especially to others of their kind, and it is best to keep only one of these fish in an aquarium setting. Keeping two or more will most likely lead to injuries and possibly even death for at least one of the fish.