Abstract: A 45 day feed study aimed to evaluate the effects of cornmeal and in natura mango at different concentrations of carbohydrates and proteins on performance, hematology, metabolism and digestive enzymes of tambqui, Colossoma macropomum. In the experiment, 144 juveniles were randomly distributed in a factorial scheme where eight experimental diets (C30P30, C36P28, C42P26, C48P24, M30P30, M36P28, M42P26 and M48P24) were tested for 45 days. Performance parameters, hematological indices, metabolites and digestive enzyme activity were evaluated. The best performance was observed in the fish that received the diet C42P26 with cornmeal as a carbohydrate source. The results of glucose, triglycerides and total plasma protein had a significant effect on levels, source and interaction effect. The levels of triglycerides and cholesterol were higher in the diets with fresh mango. The activity of the enzyme glutamate dehydrogenase presented variations, modulated from the carbohydrate and protein concentrations of the diet. The digestive enzymes activity adapted to the profile of the diets tested and were not related to fish performance. It is concluded that cornmeal diet (C42P26) is the best source of carbohydrate, promoting better performanceand health of C. macropomum.