The objective was to evaluate the effects of stocking density and vitamin C supplementation under the zoo-technical, blood and bromatological parameters of juvenile Piaractus mesopotamicus. A hundred and eighty fish (10.64±1.26g) were randomly distributed in 24 boxes and two stocking densities (0.89 and 1.77kg/m³), fed for with commercial feed (60 days), supplemented with three levels of vitamin C (0, 0.5, and 1.5 g/kg of feed), in a 2x3 factorial scheme, with four repetitions. At the end of the experiment, all fish were anesthetized to collect the zoo-technical data. Three animals from each repetition were selected for blood collection, and then, all animals were euthanized and processed to determine the bromatological parameters. There was interactive effect between the vitamin C levels and the stocking densities in the blood hematological parameter and in the carcass crude protein (p0.05). There was no effect of the vitamin C supplementation levels for the evaluated zoo-technical, hematological and bromatological parameters. The density influenced on the weight gain, average final weight, specific growth rate, total and standard length. It is concluded that the vitamin C did not present alteration in the studied variables, however, the recommended stocking density for the species in this study is 0.89 kg/m³.