Water quality is the single most important environmental determinant of fish welfare in aquaculture, with oxygen, temperature, ammonia, and pH all critically affecting fish health and behaviour.
Fish welfare is inseparable from water quality management. Unlike terrestrial animals, fish cannot move away from a deteriorating environment if confined in aquaculture systems. The welfare implications of oxygen depletion, thermal stress, and toxic waste accumulation are severe and can cause mass mortality. Investing in continuous water quality monitoring, appropriate stocking densities, and modern filtration systems is both a welfare and a commercial imperative.