In order to examine the physiological effects of removal of some fish on the remaining fish in the same tank, a survey of selected stress responses was undertaken in the gilthead sea bream. Results show that a typical acute stress reaction was induced in the remaining fish after 5 minutes and that recovery was observed at 8 hours after stress for plasma cortisol and at 24 hours for plasma glucose, lactate, and hematological parameters. Results show that gilthead sea bream, Spams aurata, is susceptible to mild stress and that disruptions are maintained for several hours. These results can be useful for further studies on sea bream in aquaculture and research in which handling procedures are required, in an effort to minimize stress. © 1997 Taylor & Francis Group, LLC.