The Angelfish are some of the most beautiful of all fish. The Emperor Angelfish shown above is probably the best known of the angelfish as it is very colorful and can usually be found in paintings and t-shirts. Angelfish can be distinguished from the very similar butterfly fish by the spine found on the lower gill cover of the angelfish.
Many angelfish have different coloration as juveniles than they do as adults.
Many of the adult angelfish become territorial as they grow older and it is thought that perhaps the different coloration among the younger fish keep them from being the target of the older fish's aggression. This makes them hard to acclimate since these foods are generally not included in prepared fish foods. Angelfish must be willing to accept new foods in their diet in order to survive in an aquarium and are therefore considered difficult to keep. Feeding a large variety of foods is important in order to entice them into eating and once accomplished, they can survive for long periods of time in captivity. As an example, the aquarium in Nancy, France has kept several specimens of angelfish for over 20 years.