Immersion anaesthesia is widely used in fish handling and research, yet optimization of protocols requires not only effective immobilization but also consideration of internal physiological responses. This study evaluated the effects of immersion‐administered lidocaine (60 and 80 mg/L) as an adjuvant to clove essential oil (CEO; 100 μL/L) on anaesthesia induction and recovery in juvenile Oreochromis niloticus under tightly con...