Pacific halibut (Hippoglossus stenolepis) aquaculture is developing in North America and Norway. As a large flatfish with complex needs, its welfare in captivity requires careful attention.
Pacific halibut welfare in aquaculture is challenged by a species biology adapted to vast natural seabed ranges and solitary existence. In tanks, bottom-resting space — not water volume — is the critical density metric; overcrowding of the flat surface triggers aggression and reduces resting opportunity. Feed presentation must account for flatfish feeding posture; surface pellets are not naturally accessible to halibut feeding from the substrate. Malformations during juvenile metamorphosis, including failure of eye migration, cause chronic functional impairment. Water quality parameters, particularly temperature, must be maintained within narrow tolerances as a cold-water species. Developing welfare indicators — behavioral, physiological, and pathological — for halibut is a research priority as the industry expands.