Domestication and selection may affect fish behaviour, sometime as soon as at the first generation of domestication. However, knowledge about how both processes impact on fish spatial exploration and swimming activity still is to be improved. The objective of this experiment was (i) to evaluate spatial exploration behaviour and swimming activities of three sea bass strains having different domestication and selection levels and (ii) to analyse their responses to an acute stress. Sea bass exploration and swimming activities were studied before, during and 40 min after a stimulation (standardized fall of an object). The experimental tank was divided in to four zones, and the time spent, the distance travelled in each zone and the swimming complexity were quantified for each period from video recording. Results showed that fish from all strains presented the same flight response and that stimulus exposure induced a significant decrease in exploratory behaviour and swimming activity. The present study has also demonstrated that only one generation of captivity could be sufficient to obtain fish presenting the same behavioural characteristics than fish reared since at least two generations. Moreover, this study has highlighted that selection for growth seemed to select fish characterized by a bolder personality and potentially better adapted to rearing environment. It allowed us to suggest that selection for growth may have a higher effect on fish personality than domestication only. (C) 2009 Elsevier B.V. All rights reserved.