Orientation of the catfish in uniform and nonuniform electric fields.

The ability of the catfish to orient itself according to the direction and density gradient of current was studied in behavioral experiments. The catfish was shown to possess directional sensitivity of up to 20 degrees in orientation according to the direction of an electric field. The orientational behavior was manifested at a current density of 1.5 X 10(-11) A/mm2 and a specific resistance of the water equal to 15 omega . m and is maintained on replacement of a constant current by pulsed current. In a nonuniform field, the fish were shown to be capable of orienting themselves according to the gradient of current density with a threshold value of 3.6 X 10(-12) per mm. The functional significance of the electrosensory system of the catfish is discussed.