Biofloc is a fish feeding technology based on the growth of microorganisms inside the same water body where fishes are housed. Nutrients excreted by fishes and residual from the unconsumed feed will contribute to the formation of a natural heterotrophic and phototrophic microbial community, that will be responsible for: (a) maintenance of a high water quality, (b) absorption of nitrogen compounds, (c) generation of microbial protein, (d) nutrition of fishes, (e) competition with several pathogens by repressing their growth. The growth of heterotrophic microorganisms is significantly faster than the development of nitrifying bacteria, therefore assimilation of nitrogen by heterotrophic bacteria and microalgae will occur rapidly. Optimal biofloc growth is achieved by maintaining a C:N ratio of 20, which guarantees an excellent microbial community profile. Simultaneously, the N:P ratio will influence the autotropic community that will occur in the system.
Culture of biofloc is realized in tanks, with (scheme A below) or without (scheme B below) fishes. Continuous aeration and 12 hours of light will be guaranteed.