[Orientation of the catfish in uniform and nonuniform electric fields].

Experiments with conditioning revealed that catfish showed compass orientation with precision about 20 degrees using a direction of homogeneous horizontally directed weak electric field with current density of 1.5 . 10(-11) A/mm2 in water with a specific resistance of 15 Ohm-m. Similar fields occur in their habitat. The catfish used the current density gradient for directed movements in the unhomogenous field. The lowest current density gradient in which the catfish showed the orientation behaviour proved to be 3.6 x 10(-12) A/mm2 per 1-mm distance. The possible mechanism of electro-orientation and its functional significance, are discussed.