Anesthesia for fish in research and aquaculture settings reduces stress during handling procedures and represents an important welfare improvement over unanesthetized handling.
Fish anesthesia represents a clear welfare improvement for procedures including surgery, tagging, sampling, and transport. Anesthetized fish do not show the escape responses, cortisol surges, and physiological stress of fully conscious fish undergoing handling. The welfare case for anesthesia use is supported by the same evidence base that supports fish sentience: if fish experience stress and potentially pain, minimizing those experiences through anesthesia during unavoidable procedures is the appropriate welfare response. Barriers to wider adoption include cost of pharmaceutical anesthetics, recovery time in commercial aquaculture settings, and the regulatory burden of using licensed compounds. Research into alternative anesthetic agents and development of aquaculture-compatible protocols are needed to extend the welfare benefits of anesthesia to commercial-scale fish handling.