Nonfaecal and faecal losses of Pomadasys commersonni (Teleostei: Pomadasyidae) feeding on the surf clam, Donax serra.

1. The nonfaecal and the faecal production of Pomadasys commersonni, a marine teleost, were investigated at 15, 20 and 25 degrees C. 2. Nonfaecal nitrogen excreted by starved and fed P. commersonni consisted mainly of ammonia-N. 3. The mass component b of the equation, AE = aMb (AE, ammonia-N in Mg-N/hr; M, fish mass in g) ranged from 0.68-0.72 and 0.71-0.75 for starved and fed fish, respectively, and was temperature-independent. 4. The mean percentage of the food energy lost as nonfaecal energy (exogenous plus endogenous) was 4.38 +/- 2.68%. 5. The faeces had a low energy content and ranged from 2.09 to 4.25 kJ/g. 6. Assimilation efficiencies showed some variation and ranged from 7.34 to 99.34% for dry matter and from 96.02 to 99.89% for energy. 7. The mean combined energy loss was 11.77% of the ingested energy.