Bioflocs Technology in Freshwater Aquaculture: Variations in Carbon Sources and Carbon-to-Nitrogen Ratios

Aquaculture is one of the fastest food-producing sectors contributing half of the food fish destined for human consumption. Nevertheless, aquaculture production still needs to increase to fill the gap in supply and demand for fish, as the capture fisheries are stagnating over the years. Therefore, intensification of aquaculture production systems by increasing inputs such as feed has been devised as an alternative. On the other hand, intensive aquaculture has been associated with concerns related to environmental pollution in the past decades. Moreover, the increased cost of feed ingredients for aquaculture species has hampered the intensification of the sector. Therefore, alternative production systems such as biofloc technology were developed to mitigate the environmental impacts of intensive aquaculture and also to produce extra feed for cultured organisms. Due to their omnivorous feeding habit and tolerance to higher levels of suspended solids, freshwater finfishes have been the most cultured species in this system. The organic carbon sources used in the biofloc system are agricultural and industrial by-products which are cheap and readily available, making the technology economically feasible. C:N ratios of 10, 15, and 20 have been the most applied C:N ratios in the culture of freshwater aquaculture finfishes covered in this review.