Cannabidiol and microbubble aeration enhance stress resilience and physiological homeostasis in European sea bass: a multi-tissue integrative approach

Abstract

Introduction: Animal welfare has become an increasingly important issue in the aquaculture sector, and improving it is essential for maintaining the health of farmed fish. Therefore, the aim of the present study was to evaluate the potential effect of dietary cannabidiol (CBD) supplementation (0.001%) environmental enrichment (EE) through modified aeration or their combination over 5 weeks to assess their suitability as strategies for improving welfare in aquaculture. Methods: Methods: After this period, fish were subjected to a confinement stress challenge. Welfare indicators such as survival, selected stress and immunological parameters, lipid mediators, and the expression of several stress-response and appetite-regulating related genes in different brain regions (including telencephalon, hypothalamus, and pituitary gland) were analysed in European sea bass. Results: The results showed that survival rates were significantly higher in all welfare-promoting groups; EE improved production parameters and increased dissolved oxygen levels; CBD treatments did not negatively affect growth performance, reduced plasma cortisol during both acute and adaptive stress responses, enhanced basal serum lysozyme activity, and promoted a faster post-stress stabilization; and the combined treatment supported a synergistic interaction between EE and CBD, in which lipid mediators suggested modulations of inflammatory responses under stress and helped to mitigate the effects of the stress response-related genes and a potential involvement in appetite regulation and energy balance strategies. Discussion: These results highlight the potential of microbubble curtain enrichment and CBD for improving welfare of juvenile sea bass, enhancing growth, stress resilience, and physiological regulation, with the combined treatment showing the strongest and most effective improvements.