Summary
An overview of the families, genera and some species of the Gymnotoidei is presented with a review of their behaviour and natural history. Characteristics of the electric organs and electric organ discharge (EOD) for various species are presented. The role of EOD on the animal's life is discussed, especially as it relates to behaviour and other events. Electroreception, its special sense organs and brain-processing, including use by non-electric fish is discussed. The results of these studies are interpreted in terms of their pratical and ecological significance in the life of this group of fish.