ABSTRACT
The microbial cells, which are linked to the surface and bound to the matrix of primary polysaccharides materials, are collectively called biofilms. The surface can be a medical device, water pipe, living tissue, and simply a natural aquatic environment. The assemblage of biofilms contains simple unicellular and multicellular organisms, like algae, protozoa, bacteria, and arthropods. The structure of biofilms fully depends on the light and grazing capability of the organism, nutrient availability, hydrodynamics of system, and most importantly the nature of the substratum. The introduction of substrata plays a significant role in the development of biofilm, and organic substrata facilitate more growth of microbial colonies on them. Biofilms are rich in single-cell proteins, which can be very easily harvested and digested by aquaculture species as natural feed sources. Most biofilms provide up to 40% protein, which satisfies the protein demands of many cultured finfish and shellfish species. Besides being a source of nutrition, the heterotrophic bacteria and microalgae also act as immune system modulators, growth enhancers, bioactive compounds, and dietary stimulants. Substrata also increase the survival rate by providing the attachment sites, shelter, and hiding places to aquatic animals. The biofilms play a significant role in the improvement of water quality parameters and in the reduction of pathogenic bacteria through nitrification of ammonia to less toxic nitrates. Therefore, biofilms provide a cheap source of nutrition and water quality control to a poor farmer for sustainable aquaculture. This chapter spotlights the importance of biofilms in the sustainable production of aquaculture.
