Light management in fish farming affects feeding behaviour, growth, reproduction, and stress levels. Getting lighting right is an important and often overlooked welfare intervention in aquaculture.
Light is a fundamental environmental parameter for fish, shaping their daily rhythms, reproductive cycles, and stress responses. In aquaculture, lighting is often manipulated for production reasons — suppressing maturation, extending feeding activity, or accelerating growth — without full consideration of welfare consequences. Continuous lighting, used in some salmon systems, disrupts natural circadian rhythms and is increasingly associated with welfare concerns including abnormal melatonin profiles and altered immune function. The transition to LED lighting in modern aquaculture facilities creates an opportunity to design light regimes that serve both production and welfare goals — matching natural cycles more closely while using specific wavelengths that reduce aggression or fear responses. Welfare-optimised lighting is increasingly feasible and is beginning to be incorporated into better certification standards.