The cusk eel family consists of over two hundred species of bony, marine fish found in tropical and temperate oceans all around the world. They live close to the bottom of the sea, ranging from the shallows to depths of over 6562 feet (2000 meters). The largest known species of this family grows up to about 6.6 feet (2 meters) long, but most species are smaller than 3.3 feet (1 meter). Cusk eels are not related to true eels, and can be distinguished from them by their ventral fins. Ventral fins are a pair of fins in a fish's pelvic girdle that help in controlling movement. True eels don't possess these fins, whereas in cusk eels they have developed into forked, barbel-like organs below the mouth. As with true eels, however, the dorsal, anal and tail fins of cusk eels are formed into a single long fin.