The behavioural and metabolic responses of the largemouth bass Micropterus salmoides (Lacépède) to temperature were determined to define optimal thermal conditions. The final preferendum of largemouth bass juveniles determined with acute and gravitation methods was independent of the method (29.0–28.1 °C). The displacement velocity in the horizontal thermal gradient of bass juveniles was 22.4 cm h⁻¹ in the light phase and 22.6 cm h⁻¹ in the dark phase. Oxygen consumption rates in the largemouth bass increased significantly (P<0.05) from 48.8 to 69.4 mg O₂ Kg⁻¹ h⁻¹ with an increase in the acclimation temperature from 20 to 33 °C. The temperature quotient (Q₁₀) in the juveniles was 1.37–2.00 in the range of acclimation temperatures of 26–29 and 29–32 °C. The optimum temperature range for growth calculated using Jobling's equation was 28.1–28.6 °C and for Q₁₀ values 26–29 °C. The results are discussed in relation to the use of this information in aquaculture.