High Coverage Koi Angelfish were developed by selectively breeding the classic Koi Angelfish to have more and more orange covering the body of the fish. They are a very unique color of Angelfish that will surely stand out in the aquarium. Angels can grow to be quite big, and should need at least 20 gallons of tank space once they are full grown. Angelfish have long ventral fins that flow gracefully as they swim throughout the tank. Their long dorsal and anal fins give them a lot of height, so taller tanks are recommended for these fish. Once they get adjusted to the aquarium, you can see how eager they are to eat. They swim right up to the front whenever they think they are about to be fed. Angelfish can get aggressive once they are mature, so adding in decorations or plants to block their line of sight in the tank would help reduce aggression.