Gymnotus electricus attains a length of 3 ft.
Gymnotus is the only genus of - the family which possesses electric organs.
The family comprises a single genus, Gymnotus, which holds some of the most abundant and familiar knife fish from the Amazon.
The maximum shock is given when the head and tail of the Gymnotus are in contact with different points in the surface of some other animal.
The most interesting and the best known of these singular fishes is the Gymnotus or Surinam eel.
The power of giving electric shocks has been discovered also in the Gymnotus electricus (electric eel), the Malapterurus electricus, the Trichiurus electricus, and the Tetraodon electricus.
They resemble the latter in the elongation of the body, the large number of vertebrae (240 in Gymnotus), and the absence of pelvic fins; but they differ in all the more important characters of internal structure.