Adult tilapia in grow-out ponds and tanks face welfare challenges from high stocking densities, male aggression, and stressful harvest procedures that affect millions of fish daily.
Adult tilapia welfare is compromised by the same high-density conditions as fingerlings, now complicated by the social complexity of sexually mature fish. Male aggression — fighting for territory and mates — causes injury and chronic stress in mixed-sex populations, which is why most commercial operations use all-male monosex populations. However, all-male production relies on hormonal sex reversal with ongoing welfare questions. High stocking densities that tilapia tolerate physiologically still cause behavioral restriction and stress. Harvest procedures — netting, crowding, and air exposure — cause acute suffering. Live fish markets where tilapia are kept in poor conditions for sale represent a significant welfare concern across Asia and Africa. Improving welfare at harvest and in live markets could benefit enormous numbers of animals.