The queen angelfish, native to the eastern and western Atlantic Ocean from the United States to Brazil, South America, is a popular choice for experienced aquarium owners. Also known as Holacanthus ciliaris, the fish has a compressed blue and yellow body up to 18 inches (45.72 cm) long, with a beak-shaped mouth. A dark spot at the top of its head is ringed with blue, creating a crown-like appearance from which the fish gets its name. Young queen angelfish are darker and have white stripes toward their rear. The species is also known by the names queen angle, blue angelfish, yellow angelfish, and golden angelfish.
Queen angelfish normally live in water that is up to 230 feet (about 70 meters) deep, and it requires sufficient space to live comfortably. To keep one in an aquarium, 150 gallons (575 liters) of water is the minimum requirement. The reef fish are sensitive to the environment, and the water should be between 72° and 78°F (22° and 25.5°C) with a pH value from 8.1 to 8.4. Nitrates should be kept to a minimum as well, and all of these criteria should be established before the fish is added to the aquarium.
Sponges are the favorite food of queen angelfish, and they also eat plankton, algae, and jellyfish. As juveniles, they will eat parasites off of other fish in the ocean. There are frozen foods sold in stores that contain sponge material, along with dried algae and vitamin supplements that are healthy for the fish. They will also eat shrimp, shellfish, and squid. Soft corals are also a favorite, so a home aquarium should include these as well as rocks that can support the growth of algae.
Whether living in the ocean or in a home aquarium tank, a queen angelfish retains its natural instincts. It can be aggressive and territorial, and having more than one of the same species in the same tank can result in aggressive fights between the fish. Aggression toward other angelfish species is possible but not as common. While it does not associate well with similar species, the queen angelfish sometimes mates with the blue angelfish, which results in rare hybrid offspring. It also likes to be out in the open, but unless there are a couple of hiding places, such as pieces of coral, it can become stressed.