Common sole (Solea solea) is farmed as a premium flatfish species. Its benthic lifestyle and specific dietary needs create distinct welfare challenges in intensive production.
Common sole face distinctive welfare challenges in aquaculture because of their specialized lifestyle and feeding biology. In recirculating systems, providing adequate substrate contact and appropriate lighting levels for their benthic preference is difficult in standard tank designs. Sole in flat-bottomed tanks with adequate substrate show more natural resting behavior and lower stress indicators than those in deep tanks without substrate access.
Feeding is a significant welfare challenge. Sole locate food primarily through chemoreception, not vision — they need to physically encounter food particles to detect them. Formulated pellet diets are accepted only after conditioning, and feeding efficiency in large groups is reduced by competitive interference. Hungry sole show increased cortisol and abnormal food-searching behaviors that indicate welfare-relevant frustration.
Welfare improvements center on system design (flat tanks with substrate), feeding management (small frequent feeds, appropriate pellet texture), size grading to minimize aggression, and humane slaughter through electrical stunning or percussion before bleeding. Research into sole-specific welfare indicators is advancing through European aquaculture research programs.