In this investigation, the effects of an anesthetic, quinaldine sulphate (QS), and a muscle relaxant, diazepam (D), on sea bream juveniles (Sparus aurata) were studied. The application of diazepam significantly increased the safety level of the anesthetic QS for the sea bream juveniles. The fish entered light anesthesia at 5 ppm QS + 1 ppm D, as compared to 10 ppm QS. Similarly, the deep anesthesia level was reached at only 7.5 ppm QS + 1 ppm D as compared to 15 ppm QS. The use of QS alone at high concentrations (15-20 ppm) resulted in mortality of 30% to 100%. No mortality occurred in the fish treated with QS plus D at all anesthesia levels. Depending on the anesthetic concentrations used, the time to loss of balance and the recovery time were 0-2 min and 2-6 min, respectively. Administration of diazepam with a lower concentration of QS significantly enhanced the anesthesia, eliminated the undesirable effects of QS and reduced the excitement and hyperactivity of the fish in the confined space, without leading to mortality. Suitable light and deep sedation stages of anesthesia for transportation and handling of sea bream juveniles (6-7 g) were obtained with dosages of 5 ppm QS + 1 ppm D and 7.5 ppm QS + 1 ppm D, respectively.