An assay on tilapia Oreochromis niloticus and freshwater prawn Macrobrachium americanum in polyculture was conducted during 112 days to study the effect on their blood chemistry and biochemical body composition to determine the feasibility of this polyculture in high density. Six densities were evaluated [T4/5, T9/5, T14/5, T0/5, T9/0, and T14/0; Ttilapia/prawn (ind m-2)]. In tilapia were evaluated hemoglobin, red cells albumin, globulin, cholesterol, glucose, and triglycerides composition in blood. In M. americanum were evaluated hemocyanin, cholesterol, triglycerides, glucose and total protein in hemolymph. The total content of proteins, lipids, and carbohydrates in muscle and liver of tilapia, and muscle and hepatopancreas on prawns were also studied. Both animals presented significant differences (P < 0.05) in the glucose concentration, tilapia at T9/5 density presented significantly lower concentration (26.25 ± 6.3 mg dL-1) in blood, and prawn at T4/5 presented significant higher concentration (12.2 ± 1.9 mg dL-1). Tilapia monocultures T14/0 displayed significant higher (P < 0.05) carbohydrate concentration in muscle. No significant differences (P > 0.05) appeared in the concentration of lipids and proteins in any tilapia group and proximal composition of muscle and hepatopancreas in prawn. The present study indicates that polyculture in a density T14/5 is similar than monoculture with no effect in blood or hemolymph chemistry and proximal composition of tilapia and prawn. The blood glucose concentration can be considered an indicator of physiological changes for tilapia and prawn when cultured together.  An assay on tilapia Oreochromis niloticus and freshwater prawn Macrobrachium americanum in polyculture was conducted during 112 days to study the effect on their blood chemistry and biochemical body composition to determine the feasibility of this polyculture in high density. Six densities were evaluated [T4/5, T9/5, T14/5, T0/5, T9/0, and T14/0; [Ttilapia/prawn (ind m-2)]. In tilapia were evaluated hemoglobin, red cells albumin, globulin, cholesterol, glucose, and triglycerides composition in blood. In M. americanum were evaluated hemocyanin, cholesterol, triglycerides, glucose and total protein in hemolymph. The total content of proteins, lipids, and carbohydrates in muscle and liver of tilapia, and muscle and hepatopancreas on prawns were also studied. Both animals presented significant differences (P < 0.05) in the glucose concentration, tilapia at T9/5 density presented significantly lower concentration (26.25 ± 6.3 mg dL-1) in blood, and prawn at T4/5 presented significant higher concentration (12.2 ± 1.9 mg dL-1). Tilapia monocultures T14/0 displayed significant higher (P < 0.05) carbohydrate concentration in muscle. No significant differences (P > 0.05) appeared in the concentration of lipids and proteins in any tilapia group and proximal composition of muscle and hepatopancreas in prawn. The present study indicates that polyculture in a density T14/5 is similar than monoculture with no effect in blood or hemolymph chemistry and proximal composition of tilapia and prawn. The blood glucose concentration can be considered an indicator of physiological changes for tilapia and prawn when cultured together.