The evolution of increased thermal tolerance in aquatic ectotherms may affect genetically correlated traits and alter physiological performances. Here, we report the correlated responses of a range of life history, behavioural and physiological traits to seven generations of artificial selection for increased (Up-selected) or decreased (Down-selected) acute upper thermal tolerance limit (CTmax) in zebrafish (Danio rerio). Contrary to the prediction of a trade-off between warming and cooling tolerance, the thermal window increased in the Up-selected lines. No change was observed in the aerobic metabolic scope or in the thermal sensitivity of resting and maximum metabolic rates, thus contradicting the hypothesis that thermal tolerance limits are controlled by aerobic scope. We also found no difference in brain heat shock protein levels between the selected lines, contradicting the hypothesized role of heat shock protein expression in the evolution of acute warming tolerance. Finally, fecundity, growth and swimming speed did not change in the Up-selected lines, but tended to decrease in the Down-selected lines, suggesting that the evolution of lower thermal tolerance is accompanied by a decrease in individual quality. These results suggest that selection due to acute heating events can benefit tolerance to cold, making individuals more resilient to extreme temperature events.