Physiological stress response of Brown bullhead (Ameiurus nebulosus) was studied under laboratory conditions. This species is well known for the resistance and adaptability to environmental factors. In this sense, metabolic and hematologic profiles were determined for low (6 C), medium (18 C) and high (31 C) water temperatures. An increase in blood cell numbers (RBC, WBC) and hematocrit (Ht) was determined under high temperature conditions, as a response to low dissolved oxygen. Platelet count (PLT) remained relatively constant regardless of the water temperature. The metabolic profiles showed significant and very significant differences for most of the analyzed indices. The differences were due to variations in temperature that influenced appetite and ingestion of feed, respectivelly the respiratory function by vasoconstriction or hypoxia.