Fish anesthesia is widely used in aquaculture for handling, transport, and research procedures; appropriate agent selection and concentration are critical for welfare outcomes.
Fish anesthesia welfare depends critically on appropriate agent selection, concentration management, and recovery conditions. Under-dosing produces inadequate sedation while fish remain conscious of stressful handling; over-dosing causes toxicity and death. The interaction between water temperature, fish species, individual size, and anesthetic concentration makes protocol standardization important for consistent welfare outcomes. Many aquaculture operations using anesthesia for transport, vaccination, and health assessment have inadequate protocols or monitoring. Research facilities using fish anesthesia for experimental procedures have stronger regulatory guidance but variable implementation quality. The welfare case for proper anesthesia use — reducing handling stress, pain from invasive procedures, and injury from struggling — is strong and evidence-based.