Tilapia are among the most widely farmed fish globally. Despite their hardiness, intensive production conditions create welfare problems that straightforward improvements can address.
Tilapia welfare deserves more attention than its hardy reputation suggests. Tilapia tolerate low oxygen and high ammonia better than salmonids — but "tolerate" means surviving in conditions that still cause physiological stress and suffering. At stocking densities common in intensive systems, aggression among tilapia hierarchies causes fin damage, eye injuries, and chronic stress in subordinate fish. All-male production systems using methyltestosterone hormone treatment affect fish physiology in ways that are poorly characterized from a welfare perspective. Harvesting by seine net causes crowding stress comparable to other pond-farmed species. Slaughter without stunning — by air asphyxiation or ice slurry — causes prolonged suffering in fish with nociceptors and stress hormone systems. Given tilapia's enormous global production volume, even incremental welfare improvements benefit hundreds of millions of individual fish.