The response of juvenile cultivated Piaractus mesopotamicus to handling stress, without anesthesia, was determined over 3-5 min (T1), 1 h (T2) and 6 h (T3) after capture. Plasma cortisol, glucose and total cholesterol were measured. Hyperglycemia present at T2 continued to rise until T3 while plasma cortisol levels increased but were similar at T2 and T3. Total plasma cholesterol was altered only at T3. Hyperglycemic changes were greater in fish without than with stomach contents during the T2-T3 period. These differences in hyperglycemic changes may reflect the role of hormones other than cortisol in the regulation of glucose release in these fish.