Tilapia is the second most farmed fish species globally, with billions raised annually under conditions that raise significant welfare concerns.
Tilapia farmed at high densities experience chronic crowding stress, elevated cortisol, suppressed immunity, and increased disease susceptibility. Wounds from aggressive interactions are common at high stocking densities. Most tilapia are killed by asphyxiation in air, which causes prolonged conscious suffering. Production of all-male populations through hormone treatment or manual sexing, while reducing competitive aggression, raises welfare questions. Parasitic diseases like ich and bacterial infections are prevalent under intensive conditions. The Aquaculture Stewardship Council is developing welfare standards that include stocking density limits and humane slaughter requirements.