Abstract: An apparatus for aerating fish ponds utilizes a cylindrical brush mounted for rotary motion below the top of a dam or headwall. Water passing over the dam and falling into a fish pond below the dam falls onto and over the cylindrical brush causing the brush to rotate. The rotating brush breaks up the falling water into droplets as the water passes through the brush bristles. Below the rotating brush, the water droplets fall through an air-water mixing zone where atmospheric oxygen is dissolved by the water droplets thus increasing the dissolved oxygen concentration of the water.