Heatwaves and hypoxic events are major stressors for marine fishes in an era of global change. We investigated impacts of these extreme events on growth and indicators of metabolism in the three genetically distinct populations of European seabass, Atlantic (AT), West and East-Mediterranean (WM, EM). Fish were reared in common garden in three seasonal thermal regimes that reflect their natural environments (eAT 10.2-18.4°C; eWM 12.5-23.0°C; eEM 16.7-28.0°C) and, at peak summer temperature, subsamples were weighed, measured and exposed in triplicate for 10 days to a heatwave (+4°C), hypoxia (50% saturation), heatwave+hypoxia, or control. At the end of the events, weight and length were measured, and blood samples were collected to measure plasma indicators of energy and hydromineral homeostasis (glucose, lactate, triglycerides, protein, calcium, chloride, sodium, osmotic pressure). By comparison to the control, in eAT warming from 18.4 to 22.4°C stimulated feeding and growth, an effect abolished by hypoxia and hypoxia+heatwave. In eWM, there was little effect of heatwave or hypoxia on growth, but heatwave+hypoxia caused some inhibition. In eEM, all the extreme events caused loss of appetite and weight loss. Despite evolving in different thermal environments, the three populations did not differ in the effects of the extreme events on growth, plasma indicators are being analysed. The results demonstrate that heatwaves can be beneficial for growth in cold environments, that seabass are resilient to moderate hypoxia even when in combination to a heatwave, but extreme events clearly have negative effects in warmer environments.