The aquaculture industry is growing fast at a rate of~ 9% per year since the 1970s. However, this industry has come under scrutiny for contribution to environmental degradation and pollution. As a result, requirement for more ecologically sound management and culture practices remains fully necessary. Moreover, the expansion of aquaculture is also restricted due to land costs and by its strong dependence on fishmeal and fish oil. Such ingredients are one of the prime constituents of feed for commercial aquaculture. Feed costs represent at least 50% of the total aquaculture production costs, which is predominantly due to the cost of protein component in commercial diets. Interest in closed aquaculture systems is increasing, mostly due to bio-security, environmental and marketing advantages over conventional extensive and semi-intensive systems. When water is reused, some risks such as pathogen introduction, escapement of exotic species and discharging of waste water (pollution) are reduced and even eliminated. The environmental friendly aquaculture system called “Biofloc Technology (BFT)” is considered as an efficient alternative system since nutrients could be continuously recycled and reused. The sustainable approach of such system is based on growth of microorganism in the culture medium, benefited by the minimum or zero water exchange. These microorganisms (biofloc) has two major roles:(i) maintenance of water quality, by the uptake of nitrogen compounds generating “in situ” microbial protein; and (ii) nutrition, increasing culture feasibility by reducing feed conversion ratio and a decrease of feed costs. The objective of this chapter is to review the application of Biofloc Technology (BFT) in the aquaculture system and describes the utilization of biofloc biomass as an ingredient for compounded feeds. An addition goal is to clarify the basic aspects of such technology, aiming to encourage further research.