Stocking density in fish farms directly affects welfare through competition, aggression, disease risk, water quality, and physiological stress responses.
Stocking density is one of the most studied welfare parameters in aquaculture. Research consistently shows that welfare indicators - cortisol levels, fin damage, growth performance, immune response - deteriorate above species-specific thresholds. Lower-density systems produce fish with better welfare outcomes and often better product quality. Certification schemes like the Aquaculture Stewardship Council include density limits as welfare criteria. The economic pressure to maximize production per unit of water volume conflicts directly with individual fish welfare.