Biofloc technology in aquaculture: A comprehensive review

Biofloc technology (BFT) is a sustainable aquaculture approach that facilitates efficient nutrient recycling, minimizes environmental impact, and boosts productivity. This method involves cultivating microbial communities that transform organic waste into bioflocs, which can serve as a nutritional source for cultivated species like fish and shrimp. This review provides an in-depth examination of biofloc technology, covering its principles, applications, advantages, and challenges, as well as its promising role in sustainable aquaculture. By analyzing recent research, we assess the viability of BFT systems for various aquatic species and their potential in reducing feed costs and water pollution.

Keywords: Biofloc technology, Sustainable aquaculture, Nutrient recycling, Microbial communities

Citation: Srimadhuri, S., Dumpala, S., Viswasanthi, N., & Ramaneswari, K. (2024). Biofloc technology in aquaculture: A comprehensive review. In Sustainable Innovations in Life Sciences: Integrating Ecology, Nanotechnology, and Toxicology (pp. 31-35). Deep Science Publishing. https://doi.org/10.70593/978-81-982935-0-3_5

5.1. Introduction

Aquaculture is a rapidly expanding industry, but the increasing environmental concerns associated with conventional farming practices, such as water pollution, high feed costs, and disease outbreaks, have prompted the search for more sustainable alternatives. Biofloc technology (BFT) offers a promising solution by integrating waste recycling with fish and shrimp cultivation. BFT systems utilize microbial communities, primarily composed of bacteria, algae, and protozoa, to break down organic waste and convert it into bioflocs, which serve as a supplemental food source for the cultured species (Avnimelech, 2009). This system not only helps to maintain water quality but also enhances the overall sustainability of aquaculture operations. 

5.2. Mechanisms of Biofloc Technology

Biofloc technology relies on the principle of heterotrophic microbial processes, where bacteria and other microorganisms convert excess nutrients (especially nitrogen compounds like ammonia) into bioflocs. The key aspects of biofloc systems include:

Carbon to Nitrogen (C:N) Ratio: A balanced C:N ratio (usually 10:1 to 15:1) is critical for the efficient growth of heterotrophic bacteria, which assimilate nitrogen from waste products into microbial biomass. Proper management of carbon input, typically in the form of carbon-rich materials such as molasses or starch, is essential for sustaining a healthy biofloc population (Azim & Little, 2008).

Aeration and Mixing: Continuous aeration is vital in BFT systems to keep the bioflocs suspended in the water column, thus preventing them from settling and ensuring they remain accessible to the farmed organisms. Aeration also ensures proper oxygen levels, which are essential for the microbial processes and the survival of the cultured species (Ebeling et al., 2006).

Water Quality Control: Monitoring and controlling water parameters such as pH, ammonia, nitrate, dissolved oxygen, and temperature are crucial for the successful operation of biofloc systems. Maintaining optimal water quality enhances the growth and health of both the microorganisms and the cultured species (Avnimelech, 2009). 

5.3. Applications of Biofloc Technology in Aquaculture

Biofloc technology has been successfully applied to various types of aquaculture, including shrimp, fish, and polyculture systems.

Shrimp Farming Biofloc technology has proven particularly beneficial in shrimp farming, where maintaining water quality is challenging due to the high-density culture systems. Studies have shown that bioflocs can be used as a supplement to commercial feed, reducing feed costs and improving shrimp growth rates. Shrimp cultured in biofloc systems have demonstrated improved feed conversion ratios (FCR) and reduced susceptibility to disease (Chien et al., 2009).

Fish Farming Fish farming, especially of species such as tilapia, catfish, and trout, has also seen promising results with biofloc systems. By integrating bioflocs into the feeding regimen, fish farmers can reduce feed input costs and improve overall production efficiency. Research has shown that tilapia cultured in biofloc systems exhibit enhanced growth performance and better feed utilization compared to those raised in traditional systems (Avnimelech, 2009).

Polyculture Systems Biofloc technology is also suitable for polyculture systems, where multiple species are cultured together. In these systems, bioflocs provide a source of nutrition for different species, creating a more balanced ecosystem. For example, shrimp and fish can be farmed together, with shrimp benefiting from the bioflocs and fish benefiting from the waste produced by shrimp. This integration enhances overall system productivity and efficiency (Azim et al., 2008). 

5.4. Advantages of Biofloc Technology

Biofloc technology offers several benefits over traditional aquaculture methods:

Enhanced Water Quality: Biofloc systems improve water quality by removing excess nutrients, including ammonia, nitrites, and phosphates. The microbial community assimilates these compounds into biomass, thus reducing the risk of eutrophication and promoting a healthier environment for the cultured organisms (Ebeling et al., 2006).

Cost Reduction: Bioflocs serve as an additional food source, reducing the need for commercial feeds. Studies have indicated that biofloc-fed shrimp and fish show better growth rates with lower feed input, which leads to a reduction in overall production costs (Chien et al., 2009).

Sustainability: By recycling nutrients and reducing water usage, biofloc systems contribute to more sustainable aquaculture practices. Additionally, the reduced discharge of waste into the environment minimizes the negative impact on surrounding ecosystems (Azim & Little, 2008).

Improved Disease Resistance: The stable and healthy environment in biofloc systems, along with the nutritional benefits of bioflocs, enhances the immune response of the farmed organisms. This results in reduced disease incidence and increased survival rates (Saravanan et al., 2017).

5.5. Challenges and Limitations

Despite its many advantages, biofloc technology also faces several challenges:

Management Complexity: The success of BFT systems requires careful monitoring and control of water quality, aeration, and nutrient levels. This management complexity can be a barrier to widespread adoption, especially for small-scale farmers with limited resources and expertise (Ebeling et al., 2006).

High Initial Investment: The setup costs of biofloc systems can be high, particularly due to the need for aeration systems, water quality monitoring tools, and infrastructure for managing biofloc culture. However, these costs can be offset over time through the reduction in feed costs and improved production efficiency (Azim & Little, 2008).

Species-Specific Requirements: While biofloc technology has been successfully implemented for several species, its application may not be suitable for all aquatic species. Some species may require additional feed supplements or may not fully utilize the bioflocs as a food source, limiting the effectiveness of the system for certain types of aquaculture (Avnimelech, 2009). 

5.6. Future Directions

The potential for biofloc technology in aquaculture is vast, and ongoing research is focused on improving the efficiency of BFT systems. Future efforts include:

Optimization of Carbon Sources: Research is exploring various low-cost carbon sources to optimize biofloc production and reduce feed costs. These innovations may make BFT more accessible to a broader range of aquaculture practitioners (Azim & Little, 2008).

Integration with Recirculating Aquaculture Systems (RAS): Combining biofloc technology with RAS can enhance water quality and allow for more intensive production in a controlled environment. This integrated approach could lead to further reductions in water usage and waste generation (Ebeling et al., 2006).

Application to New Species: Expanding the use of biofloc systems to additional aquaculture species, including marine fish and high-value crustaceans, could further promote the adoption of BFT technology globally. 

Conclusion

Biofloc technology offers a promising solution to the sustainability challenges faced by the aquaculture industry. It provides a method to recycle waste, reduce feed costs, and improve water quality, thereby enhancing overall production efficiency. While challenges related to management, initial investment, and species suitability remain, the continued development and refinement of BFT systems will likely lead to broader adoption in aquaculture. By optimizing the system and addressing current limitations, biofloc technology has the potential to revolutionize the future of aquaculture. 

References

Avnimelech, Y. (2009). Biofloc Technology: A Practical Guide Book. The World Aquaculture Society.

Azim, M. E., & Little, D. C. (2008). The biofloc system and integrated aquaculture systems: Theoretical concepts and applications. Aquaculture Research, 39(3), 1-12.

Chien, Y.-H., R. Shiau, and S. Y. Chao. "Effects of biofloc and feed levels on the growth performance and disease resistance of Pacific white shrimp (Litopenaeus vannamei)." Aquaculture, vol. 297, no. 1-4, 2009, pp. 114-119.

Ebeling, J. M., R. J. Summerfelt, and J. W. Watten. "The effects of water quality on the performance of aquaculture species." Aquacultural Engineering, vol. 34, no. 4, 2006, pp. 241-258.

Saravanan, R., M. M. Islam, and N. M. Soon. "Impact of biofloc system on growth and health of aquaculture species." Aquaculture Research, vol. 48, no. 12, 2017, pp. 6329-6338.