The goal of this study was to determine the safety dosage of anaesthetic Quinaldine Sulphate (QS) alone and together with a muscle relaxant, Diazepam (D) on Convict cichlid, Cichlasoma nigrofasciatum (0.54+/-0.01 g) juveniles for ornamental fish sector. The trial showed that the QS with D administration significantly increased the anaesthesia level in the Convict cichlid. The fish entered light anaesthesia at 9.75 ppm QS+0.5 ppm D (0.83+/-0.02 min). Moreover, a deep anaesthesia level was reached at 9.75 ppm QS+1 ppm D (1.20+/-0.09 min) as compared to 13 ppm of QS (6.40+/-0.28 min). When used together with QS and D eliminated the excitement and hyperactivity of the fish compared to QS alone. In addition, no mortality occurred in any anaesthesia levels except high concentrations (40-54 ppm QS). This study indicate that the advisable light and deep phases of anaesthesia for experimental treatments, handling, immobilization and transportation of the convict cichlid juveniles were achieved with dosages of 9.75 ppm QS+0.5 ppm D and 9.75 ppm QS+1 ppm D, respectively.