The anaesthetic effects of quinaldine sulphate (QS) together with diazepam (D) on tilapia (Oreochromis niloticus) (20-25 g) were studied at different temperatures. The application of QS with D significantly increased the anesthesia level of QS in the fish. Depending on temperature, the fish entered light or deep anesthesia levels with the use of QS alone at 10 or 35 mg/l, compared to 5 or 20 mg/l when used together with D (1-2 mg/l). In addition, when used together with QS, D eliminated the excitement and hyperactivity of the fish compared to QS alone. A rise in temperature from 18 degrees C to 26 degrees C increased the level of anesthesia from light to medium or from medium to deep.