محمد حسین خانجانی

Microorganisms (MOs) are an important member of any aquaculture system. The MOs in the BFT (Biofloc Technology) system are also crucial, diverse and therefore have different roles. This study reviews the importance of biofloc organisms (BFOs) in BFT, the factors affecting their population compositions, the impact of BFOs on water quality, and applications as food source for cultivated aquatic species. Common MOs in the BFT system often include photoautotrophic (e.g. microalgae), chemoautotrophic (e.g. nitrifying bacteria), and heterotrophic organisms, including fungi, ciliates, protozoans, and zooplankton (e.g. rotifers, copepods, and nematodes). Various factors such as salinity, type of carbon source, carbon to nitrogen ratio, aeration, light, stocking density, and total suspended solids affect the quality, density, and diversity of BFOs. Various MOs show different functional characteristics and perform three main functions: (i) help to improve the water quality by removing inorganic nitrogen compounds (bioaccumulation, bioassimilation, nitrifcation, and denitrifcation); (ii) act as a supplementary food source, and (iii) create probiotic properties; key roles for any aquatic farming system.