Southern Cod-Icefishes: Notothenioidei

Most southern cod-icefishes are about 1 foot (30 centimeters) long, but some species are as short as 4 inches (10 centimeters) or as long as 6 feet (1.8 meters). Most of these fishes have black, brown, or gray mottling on a pale background. They have two or three lateral lines. The lateral (LAT-uhr-uhl) line is a series of pores and tiny tubes along each side of a fish's body and is used for sensing vibrations. Southern cod-icefishes do not have a swim bladder, an internal sac that fishes use to control their position in the water. To help them maintain their position in the water, these fishes have lighter bones than most bottom dwellers and a large amount of oil in their muscles.