Turbot farming is a growing industry in Europe and China with specific welfare challenges arising from this large, bottom-dwelling carnivorous flatfish.
Turbot welfare in aquaculture is shaped by their flatfish biology. As benthic animals requiring floor space rather than water volume, adequate tank floor area per individual is the key space parameter. High stocking densities that leave insufficient floor area cause competition, fin biting, and chronic physiological stress. Pseudoalbinism — white patches on the normally pigmented upper surface — affects 5–30% of farmed turbot and results from suboptimal larval rearing conditions, indicating developmental welfare problems during the most sensitive life stage. The intensive recirculation aquaculture systems (RAS) increasingly used for turbot require careful water quality management — ammonia accumulation and oxygen reduction cause significant stress. Handling during grading is acutely stressful. Slaughter without prior stunning causes prolonged suffering in this large, long-lived flatfish.