Temperature and dietary factors affecting the nitrogen efflux rates of the African catfish, Clarias gariepinus (Burchell)

Total ammonia and total nitrogen efflux rates of the African catfish, Clarias gariepinus (Burchell), were measured under different temperature conditions (20, 25 and 30^°C) and feeding regimes (50% protein, 40% protein and non-fed for 10 days). Both ammonia and nitrogen efflux rates were directly related to temperature. At all experimental temperatures, the 50%-protein-fed groups excreted higher levels of ammonia nitrogen than both the 40% protein and non-fed groups. No correlation of relative ammonia efflux (% ammonia/nitrogen) with either temperature or diet was observed under these experimental conditions. Such alterations caused by temperature and diet may have significant implications for an aquaculture system as low levels of dissolved ammonia are synonymous with optimum water quality.