Biofloc: A sustainable dietary supplement, nutritional value and functional properties

Finding high-value alternative protein sources for sparing fish meal (FM) in aquafeeds is one of the primary goals of nutritionists to sustainable development of the aquaculture industry. Recent research has shown that in natura (wet) biofloc biomass and dry biofloc meal (BFM) can be considered as a promising alternative to reduce dietary protein content, as well as alternative ingredient to FM and as feed additive in aquafeeds. Biofloc can contains considerable proportions of protein and lipid, and it is available ‘in situ’ throughout the day in the culture media. Biofloc is a complex combination of organic nutrients, physical substrate, and a variety of microorganisms such as zoo and phytoplankton, free and attached heterotrophic/chemoautotrophic bacteria, conglomerates of particulate organic matter, grazers (e.g., protozoa, rotifers, flagellates, ciliates, copepods), filamentous cyanobacteria, dinoflagellates, and nematodes. In addition, biofloc are bioactive compounds-rich including carotenoids, chlorophylls, phytosterols, bromophenols, amino sugars, vitamins, and minerals. Microbial derivatives such as β-1,3-glucan, poly-β-hydroxybutyrate (PHB), lipopolysaccharides, and peptidoglycans in biofloc can trigger immunostimulatory effects on the host. Also, biofloc could be a source of potential probiotics due to the presence of e.g. heterotrophic-like bacteria (e.g. , Bacillus sp. and Lactobacillus sp.). All these different mechanisms combined with its nutritional composition enable the bioflocs to perform a multifactorial effect on growth, feed efficiency, animal health and immune condition, not only in Pacific white shrimp and tilapia, but also in different aquaculture species. Based on the findings of recent studies, feed conversion rates (FCR) can be reduced by the biofloc ingestion, and about 30 to 50% of dietary FM can be replaced with BFM or floc derivatives in various farmed fish and shrimp species. The present review discusses recent advances in the application of biofloc as a dietary supplement, its nutritional value and functional properties; and brings foundation knowledge to the industry and academia regarding BFT and nutrition, the role as a sustainable production system and key research gaps. • Biofloc is a rich natural protein source available “in situ” throughout the day in rearing tanks. • Biofloc can supply a wide range of nutrients, including protein, lipids, ash, and micronutrients (fatty acid, amino acid, mineral). • Biofloc meal is an efficient protein source for inclusion in aquafeeds. • Biofloc has beneficial effects and characterization as probiotics.