Nutritional Balancing Strategies in Low-Fishmeal Aquafeeds: A PRISMA 2020-Based Systematic Review Beyond Lysine and Methionine Supplementation
Simple Summary Fishmeal remains a key functional ingredient in aquafeeds, yet its limited availability and price volatility have accelerated the transition toward low-fishmeal formulations. However, effective fishmeal reduction requires more than protein replacement, as fishmeal provides essential nutritional and functional components that support growth, nutrient utilization, intestinal integrity, immunity, and stress resistance. This review highlights nutritional strategies that enhance the performance of low-fishmeal diets, including taurine, phosphorus-mobilizing enzymes, protein hydrolysates, fermented ingredients, yeast-derived products, probiotics, minerals, vitamins, and gut health-promoting additives. Within the species, life stages, diet matrices, and experimental conditions represented in the available evidence, future low-fishmeal feeds should be developed through context-specific formulations and validation aimed at restoring the relevant biological functions of fishmeal-based diets rather than through universal ingredient or additive recommendations.