A jet aerator (1) having an aerator housing (8) that can be installed in the water discharge of a sanitary outlet fitting, and having a jet splitter (12) in the interior of the housing, dividing the inflowing water flow into a plurality of individual jets, a mixing zone (14) being disposed downstream of the splitter for aerating the individual jets, wherein at least one aerator duct (16) is provided that ends in the mixing zone (14). The jet aerator has a throttle or closing piece (18) for reducing and/or optionally activating or deactivating the aerating function, the throttle or closing piece being displaceable between an open position opening the at least one aerating duct (16) and a throttle or closing position at least partially closing the at least one aerating duct (16) by a rotary and/or sliding movement.