Compatibility. Either one Angel to an aquarium or more than 3. Angels are Cichlids and like most Cichlids, if you keep just 2 or 3 in the same aquarium, the strongest one will make the others miserable. Angels do very well in a group with 6 or more Angels in a large aquarium with at least 50 gallons of water that is at least 18" deep.
Here is a list of tropical fish that are usually compatible with Angel Fish: Silver Dollars, Bigger Tetras such as Black Skirts, Serpaes, and Silver Tips, Corydoras Catfish, Livebearers such as Platies, Swordtails, and Mollies, but not Guppies which may be eaten by Angels, and one Plecostomus Catfish.
Angel Fish are often seen in aquariums with Gouramis, Giant Danios, Rainbows, a group of Bala Sharks, and a group of Clown Loaches.
As Angel Fish grow larger, they become very efficient at stalking and eating small fish like Guppies and Neon Tetras. So they are not compatible tank mates for these fish.
Angels are susceptible to a disease called Hole in the Head. Click here for information about this disease.
Size and Life Span. Angel Fish can grow to be 12" tall and probably taller. I have seen Angel Fish with bodies 6" in diameter, but it is unusual for them to grow this big. Angel Fish are known to have lived for at least 10 years, and with exceptionally good care they can probably live even longer.