South American Knifefishes and Electric Eels: Gymnotiformes

South American knifefishes and electric eels have a narrow ribbon-like body. Instead of a tail fin, they have a long tail. The tail is an extension of the anal (AY-nuhl) fin, the fin on the midline of the belly, which on these fishes extends the entire length of the belly. There are no pelvic fins, the rear pair, or dorsal (DOOR-suhl) fin, the fin along the midline of the back. The most outstanding feature of knifefishes and electric eels is electric organs in the skin. Electric eels give off strong electric discharges. Knifefishes produce weak electrical discharges.