Microalgae as a potential ingredient for partial fish meal replacement in aquafeeds: nutrient stability under different storage conditions

Aquaculture provides half of the fish for human consumption, and the trend is on a significant rise over the coming decades. However, the soaring price of traditional ingredients used in aquafeeds is becoming prohibitive, especially in the case of capture fishery derivatives. Therefore, new alternative ingredients and additives are required in order to substitute fish meal and fish oil in aquaculture feeds. Microalgae are a reliable alternative to these as they are potential stabilizing agents against nutrient oxidation. In the present study, three experimental aquafeeds were elaborated with 15% microalgae biomass ( Isochrysis galbana , Nannochloropsis gaditana , and Scenedesmus almeriensis ); these were then stored under different temperature and light conditions for 15 months in order to analyze the stability of proteins, lipids, fatty acids, and carotenoids. The antioxidant activity of the natural pigments present in microalgae allowed frozen microalgae-based aquafeeds to maintain stable quality over 9 months of storage. Nannochloropsis- and Isochrysis -supplemented feeds had higher eicosapentaenoic and docosahexaenoic acid contents than the microalgae-free control feed. However, longer storage times led to a drop in protein and carotenoid levels.