Biofloc Technology (BFT) is an innovative and cost-effective approach in aquaculture that converts toxic materials harmful to fish and shellfish, such as nitrate, nitrite, and ammonia, into a beneficial product—proteinaceous feed. This technology is particularly useful in aquaculture systems with limited or zero water exchange, high stocking densities, strong aeration, and the development of biota through biofloc. It is especially productive in culture tanks exposed to sunlight.
How Does Biofloc Technology Work?
- Biofloc as a Wastewater Treatment System: BFT treats wastewater effectively, making it a key component in sustainable aquaculture.
- Higher Carbon-Nitrogen (C-N) Ratio: By adding a carbohydrate source, the system maintains a higher C-N ratio, which enhances water quality by producing high-quality, single-cell microbial protein.
- Heterotrophic Microbial Growth: Under these conditions, heterotrophic microbes grow rapidly, assimilating nitrogenous waste. This microbial biomass can be utilized as feed by the cultured species and also acts as a bioreactor to control water quality.
- Immobilization of Toxic Nitrogen: Toxic nitrogen species are rapidly immobilized in biofloc systems. Heterotrophic microbes have a growth rate and microbial production ten times greater than autotrophic nitrifying bacteria.
- Flocculation Principle: BFT is based on the principle of flocculation within the system.
Composition and Nutritional Value of Biofloc
- Components of Biofloc: Biofloc consists of suspended particles and microorganisms such as bacteria, algae, fungi, invertebrates, detritus, and extracellular polymeric substances.
- Formation: Biofloc is a protein-rich live feed formed by converting unused feed and excreta into natural food through sunlight exposure and vigorous aeration.
- Structure: Biofloc particles range from 50 to 200 microns in size. They are held together by bacterial mucus and filamentous microorganisms.
- Nutritional Value:
- Protein: 25-50% (dry weight)
- Fat: 0.5-15%
- Rich in vitamins and minerals, particularly phosphorus
- Acts as a natural probiotic
- Feed Ingredient Potential: Dried biofloc can replace fishmeal or soybean meal in aquaculture feeds.
Advantages of Biofloc Technology
- Eco-Friendly System: Reduces environmental impact.
- Efficient Resource Use: Minimizes land and water requirements.
- Zero or Limited Water Exchange: Operates with minimal water exchange.
- Higher Productivity:
- Enhances survival rates and growth performance.
- Improves feed conversion ratios in culture systems.
- Improved Biosecurity: Reduces water pollution and minimizes the risk of pathogen introduction and spread.
- Cost Savings:
- Reduces reliance on protein-rich feeds.
- Decreases standard feed costs.
- Reduced Pressure on Capture Fisheries: Limits the use of wild fish for fishmeal production.
Species Suitable for Biofloc Culture
Biofloc systems are best suited for species that derive nutritional benefits from consuming biofloc and can tolerate high solid concentrations in water.
- Air-Breathing Fishes:
- Singhi (Heteropneustes fossilis)
- Magur (Clarias batrachus)
- Pabda (Ompok pabda)
- Koi (Anabas testudineus)
- Pangasius (Pangasianodon hypophthalmus)
- Non-Air-Breathing Fishes:
- Common Carp (Cyprinus carpio)
- Rohu (Labeo rohita)
- Tilapia (Oreochromis niloticus)
- Milkfish (Chanos chanos)
- Shellfishes:
- Vannamei (Litopenaeus vannamei)
- Tiger Shrimp (Penaeus monodon)
Follow FisheryNews for more Information
