Effects of stunning methods on fish welfare and meat quality: A review

• This review studies the effect of stunning methods on fish welfare and meat quality • Stress-inducing methods cause anaerobic glycolysis in fish and reduce meat quality • Stress-less stunning methods are beneficial for fish welfare and meat quality • Combined stunning methods can overcome the limitations of individual ones Stunning technique greatly influences the intensity of stress response, which eventually impact the fish welfare and meat quality. This review synthesizes published data (from Web of Science, Google Scholar, and Scopus) to evaluate six mainstream stunning methods, including mechanical stunning, asphyxia, hypothermia, electrical stunning, chemical anesthesia, and gas stunning, and their impacts on fish welfare and meat quality. Highlighted findings show that stress-inducing methods (e.g., asphyxia, hypothermia, CO₂/N₂ narcosis) induce behavioral, neurological, and physiological distress, while impairing meat quality via altered pH values, rigor mortis, water-holding capacity (WHC), texture, total volatile basic nitrogen (TVB-N), color, and sensory attributes. Mechanistically, stress activates anaerobic glycolysis, causing lactic acid accumulation, muscle acidification, protein denaturation, and subsequent meat quality degradation. In contrast, stress-less methods (e.g., mechanical and electrical stunning) effectively enhance both fish welfare and meat quality. This review provides critical insights for advancing stunning technology, addressing ethical concerns, and improving meat quality in the fish industry.