Man, however, cannot direct this electricity or take it under control to use it for his own benefit. Furthermore, they are not adversely affected by this electricity. The energy they consume to defend themselves is recovered after a certain time like the charging of a battery and electrical power is once again ready for use. Fish do not use the high-voltage electricity in their small bodies only for defence purposes. Besides providing the means for finding their way in deep dark waters, electricity also helps them sense objects without seeing them.
Fish can send signals by using the electricity in their bodies.
These electric signals reflect back after hitting solid objects and these reflections give the fish information about the object. This way, fish can determine the distance and size of the object.