Flatfish including turbot, Dover sole, and halibut undergo metamorphosis from bilaterally symmetrical larvae to the asymmetric juvenile form. Welfare during this critical transition requires specialist management.
Metamorphosis welfare is a critical window — abnormal development causes permanent disability. Pseudoalbino sole and turbot cannot see normally from the blind side, reducing predator detection and competitive feeding ability. These individuals suffer ongoing welfare impacts throughout their farmed lives. Proper photoperiod and light intensity management during metamorphosis reduces abnormality rates from up to 50% to under 5% in well-managed hatcheries. Culling of severely abnormal individuals at the earliest stage minimises prolonged poor welfare.