The path to resilience: improving welfare in aquaculture through physical exercise and stressor predictability training

The aquaculture industry is growing rapidly, prompting an increased focus on improving the welfare of fish. While meeting physical, psychological, and behavioural needs remains a priority, the concept of resilience offers a deeper approach, moving beyond need fulfilment to actively enhance the capacity of fish to adapt, recover, and thrive. This scoping review assessed the evidence for resilience building in farmed fish through two forms of environmental enrichment: physical exercise and stressor predictability training. These enrichment types are described in terms of three key mechanisms involved in building resilience: coping with stress, cognitive flexibility, and behavioural adaptability. Exercise, particularly at moderate levels, can help regulate stress responses, promote neuroplasticity, and encourage positive social behaviours. Stressor predictability can also reduce the magnitude of stress responses and support proactive coping strategies by allowing fish to anticipate and prepare for environmental challenges. The relationship between resilience and fish welfare was also examined, highlighting the potential of these approaches as welfare management tools for aquaculture. The effectiveness of such interventions is likely to be species- and context-dependent, with outcomes influenced by how fish perceive and experience environmental conditions and practical constraints of large-scale aquaculture systems. However, integrating resilience-building strategies into aquaculture practices may not only enhance welfare but also improve production efficiency and economic performance, helping the industry meet societal expectations and long-term sustainability goals.