- This study evaluated ammonia (NH 3 ) emissions to the atmosphere from fishpond waters and uneaten, floating feed. Channel catfish (Ictalurus punctatus) were stocked at 550 pond -1 in four, 400-m 2 ponds at the Auburn University Fisheries Research (AUFRU), Auburn, AL, on 30 May 1997. Feed (28% crude protein), prepared as floating pellets was applied daily. Ponds were harvested between 7 and 9 Oct. 1997. Ammonia traps were placed in ponds on a weather vane sampler. Ammonia emissions were measured from June through September 1997. In addition, NH 3 volatilization from wetted catfish feed was measured in a laboratory experiment. Average NH 3 volatilization from ponds ranged between 8.8 to 71.0 mg NH 3 -N m 2 d -1 , and averaged 3.75% of total NH 3 nitrogen (TAN) concentration in water. Positive linear correlations were found between the amount of feed applied and TAN concentration in the water and between TAN and NH 3 volatilization. Volatilization from wetted feed was not a major NH 3 loss to the atmosphere. The study suggested that 24 kg ha -1 of N were lost to the atmosphere between 23 June 1997 and 30 Sept. 1997 from ponds into which 158 kg ha -1 N were applied. In the USA, there are about 66 000 ha of catfish ponds. Extrapolation from this study suggests that 1584 t of NH 3 could volatilize from catfish ponds each summer.