**2. Definition and applications of biofloc technology (BFT) in aquaculture**

Biofloc technology (BFT) is as an environmentally friendly aquaculture technique based on in situ microorganism production. Fish and shrimp are grown in an intensive way (minimum of 300 g of biomass per square meter [7]) with zero or minimum water exchange. In addition, continuously water movement in the entirely water column is required to induce the macroaggregate (biofloc) formation. Nutrients in water (in accordance with a known carbonto-nitrogen ratio of 12–20:1) will contribute naturally to a heterotrophic microbial community formation and stabilization. These microorganisms play three major roles: (i) maintenance of water quality, by the uptake of nitrogen compounds generating in situ microbial protein; (ii) nutrition, increasing culture feasibility by reducing feed conversion ratio (FCR) and a decrease of feed costs; and (iii) competition with pathogens.

BFT is considered the new "blue revolution" since nutrients can be continuously recycled and reused in the culture medium, benefited by the minimum or zero-water exchange. Also, the sustainable approach of such system is based on the high production of fish/shrimp in small areas. In addition, the bioflocs is a rich protein-lipid natural source of food available in situ 24 hours per day due to a complex interaction between organic matter, physical substrate, and large range of microorganisms. This natural productivity plays an important role recycling nutrients and maintaining the water quality. The consumption of biofloc by shrimp or fish has demonstrated innumerous benefits such as improvement of growth rate, decrease of FCR, and associated costs in feed [8].

Regarding the applications, in the past years, BFT has been used in grow-out phase for tilapia [9, 10] and marine shrimp [11, 12], nursery phase [13–15], freshwater prawn culture [16, 17], broodstock formation and maturation in fish [18] and shrimp [7–19], and as aquafeed ingredient also called as "biofloc meal" [20–22]. In addition, recently BFT also has been applied in carp culture [23], catfish culture [24], and cachama culture [25].
