African catfish in recirculating aquaculture systems represent an intensive production model with significant welfare implications from stocking density, water quality, and behavioral restriction.
African catfish RAS welfare illustrates a critical problem in aquaculture welfare assessment: physiological hardiness can mask significant welfare compromise. Clarias catfish survive conditions that would kill other species, but survival and welfare are different standards. At commercial stocking densities, catfish cannot express natural behaviors — nocturnal activity, substrate exploration with barbels, refuge-seeking — that constitute their behavioral repertoire. Chronic crowding elevates stress hormones even in tolerant species. The constant noise and vibration of RAS equipment may be particularly problematic for catfish that rely heavily on acoustic and tactile information. Better RAS welfare requires lower stocking densities, substrate provision even in small quantities, and natural lighting cycles matching the species' nocturnal nature.