The scientific seminar with the title of biofilm application in modern aquaculture was held at the conference hall by the presentation of Dr. Monireh Faeid, the researcher of the National Inland Water Aquaculture Institute, dated 14 October 2018. At this seminar, the role of biofilm in the aquatic environment, minimizing the environmental impacts, improving water quality through trapping suspended solids, breaking organic materials, increasing nitrification by microbial activity and heterotrophic production of single-cell protein were mentioned. Whatever the thickness of the biofilm is thicker, the depth that an electron acceptor must pass across the layer to interfere with another electron acceptor will be more successful. The biofilm with nitrogen uptake in fish farms reduces the incidence of diseases caused by pathogenic bacteria. Many micro-algae in biofilms are capable of producing antibiotics that prevent the growth of pathogenic bacteria. The biofilm microorganisms by increasing the immune response of aquatic species through oral vaccination in aquatic organisms provide this biomass to aquatic organisms in a cheap and natural manner. This, as a valuable resource in aquatic ecosystems, contributes to the promotion of sustainable aquaculture in developing countries.