This study was developed to evaluate the performance and carcass composition of tambatinga fingerlings, with initial weight of 6.521 ± 0.300 g, fed with isocaloric, isocalcic and isophosphoric diets (40, 37, 34, 31 and 28% of CP). Fish were cultivated for forty days in polyethylene tanks, with water recirculation system. Fishes were weighed at the beginning and at the end of the trial and the data were used for evaluation of weight gain, feed intake, apparent feed conversion, index of feed conversion, protein intake, specific growth rate and protein efficiency rate. At the beginning and end of the experiment, samples of fishes were selected for analysis of muscle composition, and the results were utilized to assess protein retention efficiency and proportion of protein and ethereal extract at weight gain. Among the performance parameters, crude protein levels influenced only protein intake and protein efficiency rate, with linear effect. Crude protein amount, proportion protein on weight gain and protein retention efficiency of the tambatinga fingerling's muscle, increased linearly with protein reduction in the diet, whereas ethereal extract and its proportion on weight gain decreased. It was concluded that the diet with 28% of protein can be used for tambatinga fingerlings without affecting performance.
fish nutrition; muscle composition; performance; protein levels
