Current producing device for cylindrical fish rearing vessels (11), having at least one supply or distributor pipe (15) for supply of water, which is located by the edge of the rearing vessel and provided with numerous nozzle openings (18). A damper (means 21) displaceable with regard to the nozzle openings (18) is arranged axially movable between lateral guides (19, 20). The nozzle openings (18) in the distributor pipe (15) is provided with axially extending slits, having a length which exceeds the width by a factor of at least (2). The damper means exhibits numerous slit openings (22), which correspond with the slit openings in the distributor pipe (15) with regard to shape and number. The damper means (21) is connected to a linear motor (23, 25) for controlling the axial movement.
