Abstract: A device for aerating a bait tank using only air flow as the source of power. An ambient air driven propeller or fan mounted on a shaft positioned in a generally cylindrical housing is provided. A crank section formed in the shaft produces a reciprocating motion which operates a piston rod that is connected to the shaft at one end and to a diaphragm or bellows having a check valve at the other end. A tube or other conduit connected to the outlet of the check valve directs a unidirectional flow of aerating air to the bottom of the tank. An air stone or air brick may be secured in the bottom of the tank in the path of the aerating air flow to enhance dispersion into the bait tank.