Turbot, halibut, and sole farming presents unique welfare challenges because flatfish lie on the bottom and require specific substrate and stocking conditions to avoid welfare compromise.
Flatfish welfare is poorly understood compared to salmon and trout, creating significant knowledge gaps in production systems. Their bottom-dwelling ecology means that conventional volume-based stocking density metrics are inappropriate — floor area per fish is the relevant measure. Inadequate floor space prevents all fish from resting simultaneously, creating perpetual competition and stress. Substrate provision can significantly reduce aggression and improve resting behaviour. The welfare case for flatfish farming improvement is strong but under-researched.