Biofloc Aquaculture: Guide for fish farmers

In contrast to RAS, where water treatment is carried out outside the culture column, biofloc technology is an in-situ water treatment technique that is a new development in fish culture systems that is moving towards assuring sustainable aquaculture (Vinatea et al., 2018). Similar to denitrification systems, biofloc technology uses a carbon supply to encourage the growth of heterotrophic bacteria that transform hazardous ammonia into nitrogen gas rather than the nitrates that build up in traditional RAS (Dauda & Akinwole, 2015). However, biofloc technology systems do not require a biofilter or external equipment, whereas denitrification systems are carried out ex-situ and require a biofilter for the growth of bacteria (Vinatea et al., 2018). The fundamental idea behind biofloc systems is to maintain a carbon-to-nitrogen ratio (C/N) balance that promotes the growth of heterotrophic bacteria, which then use ammonia to grow and release nitrogen gas from the system (Dauda et al., 2017b; Dauda et al., 2018). Heterotrophic bacteria will develop in response to a high C/N ratio of 10 to 20. These bacteria will then directly consume the poisonous ammonia from the culture environment and generate a cellular protein (Avnimelech, 2012). Because the cellular protein may be fed to the culture organisms, BFT has an extra advantage over other culture systems (Bossier & Ekasari, 2017; Gaona, Almeida, Viau, Poersch, & Wasielesky, 2017). The culture organisms can eat this suspended heterogeneous protein particle, which has been determined to be high-quality protein. In conclusion, biofloc technology can guarantee the preservation of water quality by absorbing ammonia to create microbial proteins. It can also provide food for the cultured fish by using the microbial proteins that are produced. This results in more effective use of the feed that is supplied, a lower food conversion ratio, and lower feeding costs in aquaculture.