This study focuses on the impact of possible temperature increase on tra catfish (Pangasianodon hypophthalmus) in the Mekong River Delta. The effects of a range of different temperatures were assessed on survival rates, and physiological processes relating to growth. Two trials were conducted: (1) short-term (14 days) and (2) long-term (56 days) that investigated the impacts of temperature (24–36oC) on fish growth performance, physiological and hormonal responses. Hematological parameters including red blood cell counts, hemoglobin concentrations and hematocrits at 24oC and higher sublethal temperature (30, 32, 34 and 36oC) treatments were significantly higher than what may be considered the control temperature, 27oC. 34oC appeared to be the optimum temperature for tra catfish growth with the highest weight gain, daily weight gain, specific growth rate, with no observed decline in survival. It is suggested that maximal growth performance at 34oC was due to the more intensive metabolism, enabling greater food intake with no associated increase in food conversion ratio in comparison with other treatments as might be expected under stressful conditions. Most growth performance parameters started declining at 36oC. Providing culture environments do not rapidly increase above 34oC, cultivated tra catfish should continue to perform well.