The Black Cardinal fish, has the same basic body configuration as the Flame Cardinal fish, but has a dark black sheen. It is a very hardy fish that will do great in groups, and will spend a lot of its time looking out from the rockwork and under overhangs in your tank. If you are adding multiple Cardinal fish, it is very important to add them all at once to prevent any established Cardinal fish from picking on newcomers. With its maximum size of around three inches, it is a great size for smaller aquariums. It will accept a variety of foods, and will accept flake food.The family of Cardinalfish are a group of relatively small fish that like to inhabit reef overhangs and crevices. These fish are nocturnal and do most of their feeding at night time. They usually have large eyes, two separated dorsal fins, and short snouts. Cardinals are known for being mouth brooders where eggs are incubated inside the mouth of the fish.