Bony fishes are distinguished by the presence of bony endoskeleton. Their second noteworthy character is the presence of a swim bladder or lungs, which helps the fish to maintain its body density equivalent to that of its surrounding medium. The skin of bony fish is normally covered with overlapping scale, which are either cycloid or ctenoid. In some it become obsolete and in others it is modified by calcification to an ossified dermal covering in complete bony coating
