We report the first records of the blood parameters of T. natans for Colombia. The hematocrit was determined in standard group (GP): 41,94 ± 5,06% and experimental group (GE): 43.37 ± 6,14% by conventional method, and hemoglobin (GP:12,52 ± 3,06 g/dL; GE: 14,43 ± 3,85 g/dL), total proteins (GP:6,16 ± 0,60 g/dL; GE: 6,05 ± 6,36 g/dL), total cholesterol (GP:280 ± 50 mg/dL; GE: 281 ± 44 mg/ dL) and glucose (GP: 140,25 ± 27,96 mg/dL; GE: 120,56 ± 23,44 mg/dL, ± SD) by spectrophotometry. Our data suggest stress by pollutant agents in synergy with other factors as thermal changes.