Organic aquaculture is gaining significance worldwide due to the increasing demand for sustainable aquatic products but its development encounters various challenges, such as technical difficulties, limited profitability, and bureaucratic complexities. A critical aspect revolves around fish nutrition, particularly addressing consumer and environmental concerns. Although extensive research exists on sustainable fish feeds in conventional aquaculture, there is a notable gap in research specific to organic aquaculture. The development of innovative feeds for organic aquaculture faces challenges and costs related to the search for novel ingredients, in adequation with organic regulations. This study assessed the potential of an environmentally-friendly and cost-effective organic feed, with 51% fish meal substitution using a blend of animal and plant protein sources (i.e. , fermented soy, pea protein, yeast, krill and squid meals) for Gilthead seabream ( Sparus aurata ), a key species in European aquaculture. The development of new aquafeeds must ensure the fulfillment of developmental, physiological, and behavioral needs of animals, with a focus on achieving sustainable production performance. In a 134-day experiment, a multi-function and multi- parameter approach comprehensively assessed the effects of the novel innovative organic feed on the growth, health, and welfare of Gilthead seabream. Innovative technological tools, specifically accelerometer tags, were also utilized for continuous monitoring of energy expenditure.
Results indicated that the innovative diet had no adverse effects on the growth performance and survival of Gilthead seabream. Hematological and biochemical blood indicators showed minimal alterations, suggesting overall that welfare was not compromised. Immunological parameters suggested potential enhancement in immune defenses in fish fed the innovative diet . Finally, swimming activity, recorded by tags, showed some slight diet-related differences in acceleration values, indicating potential variations in energy metabolism. Fish fed the innovative diet showed a lower utilization of the anaerobic metabolism. A complementary multiparametric approach was applied and provided a comprehensive analysis of the global diet effects on fish health and welfare. This approach revealed a differential impact of the two diets on fish health and welfare (Fig. 1). A multicriteria decision analysis showed that the best health/welfare condition was achieved for fish fed the innovative diet.
Overall, the innovative diet shows promising results for Gilthead seabream organic aquaculture, but further investigations are essential, for instance to understand the underlying causes of observed changes in immune parameters.