Feeding-growth experiments on young black porgy (Sparus macrocephalus B., 4.17-69.05g initial weight) were carried out at four ration levels from starvation to satiation and four temperatures ranging from 14.8℃ to 26.8℃. Nitrogen excretion was calculated from the nitrogen budget (CN=FN+UN+GN). At starvation, the energy losses in excretion correlated to body weight in multiple function and the coefficient b ranged from 0.56-0.77. In feeding fish, the relationships between excretion and food consumption were positive linear functions. Stepwise regression yielded the prediction model for energy excretion as: U=0.0098+0.0539C+0.0087W-0.0003WT (r2=0.932, P<0.0001)