A combination of warm weather and cloudy days in late summer can result in low oxygen levels in fed catfish ponds. Several types of mechanical aerators are being used to maintain an adequate dissolved oxygen level in the ponds. These include air blowers, submerged pumps, and propellers. New among those being developed and tested at the Agricultural Experiment Station is a paddlewheel powered by a 1/4 hp. electric motor. In tests at the Auburn Fisheries Research Unit, a comparison between the paddlewheel and a pump circulation biofilter unit found that the paddlewheel maintained the oxygen level above 5 ppm., while the biofilter treatment allowed it to dip below 1 ppm. For an average power cost of $0.04 per kilowatt hour, the cost of paddlewheel aeration would be $0.04 per lb. of gain while the propeller-type aerator would cost $0.09 per lb. Additional tests are being conducted to evaluate the paddlewheel's effectiveness on commercial production-sized ponds.