Some fishes test their environment by generating electric fields outside their bodies (man's first contact with electricity). To send and receive electric signals, one's own or those from a neighbor, is the basis of some bony fishes' unusual sensory capacities that enable them to lead a secret, nocturnal life. This volume provides the reader with a detailed account of these fishes' biology and behavior and their sophisticated sensory capacities. The phylogenetic relationships of the fish taxa involved are discussed as well as the physiology and anatomy of the electrosensory-motor-system and the integration to form an efficient intelligence system. The main emphasis is on the descriptive and experimental analysis of electric communication behavior in a variety of species, including studies of digital signal synthesis. Whenever possible, mechanisms of communication are indicated.