What is a biofloc system?

Published on 5 December 2024 at 15:55

Biofloc technology (BFT) is an innovative approach used in aquaculture, including saltwater prawn farming, to enhance water quality and provide additional nutrition to the prawns. Here’s a brief overview:

  1. Water Quality Improvement: Biofloc technology involves the cultivation of beneficial microorganisms in the aquaculture system. These microorganisms help convert waste products, such as ammonia and nitrites, into microbial biomass.
  2. Nutritional Benefits: The microbial biomass, or biofloc, can be consumed by the prawns, providing an additional source of protein and other nutrients.
  3. Carbon-Nitrogen Balance: The system maintains a higher carbon-to-nitrogen (C:N) ratio by adding a carbon source, which promotes the growth of heterotrophic bacteria that assimilate nitrogenous waste.

Overall, biofloc technology helps in reducing the need for water exchange, improving feed efficiency, and enhancing the sustainability of prawn farming

In a saltwater shrimp biofloc system, maintaining optimal water quality is crucial for the health and growth of the shrimp. Here’s a detailed look at the water color, quality, and the necessary testing to ensure a successful biofloc system:

Water Color

  • Brown to Green: The water in a biofloc system typically ranges from brown to green. This coloration is due to the presence of microbial communities, including bacteria, algae, and other microorganisms.
  • Biofloc Particles: These particles are visible in the water and contribute to its turbid appearance. The color can vary depending on the dominant microorganisms and the system's nutrient levels.

Water Quality Parameters

To maintain a healthy biofloc system, several water quality parameters need to be monitored and controlled:

  1. Temperature: Ideally, the water temperature should be around 28°C (82°F). Consistent temperature helps maintain microbial activity and shrimp metabolism.
  2. Salinity: The salinity should be between 18-35%. Higher salinity levels help buffer other water quality parameters.
  3. Dissolved Oxygen (DO): Maintain DO levels above 5 mg/L to reduce stress on the shrimp and support aerobic microbial processes.
  4. pH: The pH should be kept between 7.5 and 8.0. This range supports microbial activity and shrimp health.
  5. Alkalinity: Alkalinity should be above 160 mg/L to moderate pH swings.
  6. Ammonia: Un-ionized ammonia (NH3) levels should be kept below 0.03 mg/L, as it is toxic to shrimp.
  7. Nitrite: Nitrite levels should be kept below 5-25 mg/L, depending on salinity.
  8. Nitrate: Nitrate levels should be kept below 150 mg/L to prevent stress and poor growth.
  9. Total Suspended Solids (TSS): TSS should be maintained between 400-500 mg/L. Too little can lead to poor production, while too much can cause gill irritation.

Testing and Monitoring

Regular testing is essential to maintain these parameters within the optimal range:

  • Temperature and Salinity: Use digital thermometers and refractometers to monitor temperature and salinity.
  • Dissolved Oxygen: Use DO meters to ensure adequate oxygen levels.
  • pH and Alkalinity: Use pH meters and alkalinity test kits to monitor and adjust these parameters as needed.
  • Ammonia, Nitrite, and Nitrate: Use chemical test kits or electronic sensors to measure these nitrogen compounds.
  • Total Suspended Solids: Use TSS meters or gravimetric methods to measure the concentration of suspended solids.

Management Practices

  • Aeration: Ensure proper aeration to maintain disolved oxygen (DO) levels and keep biofloc particles suspended.
  • Feeding: Adjust feeding rates based on shrimp biomass and biofloc activity to prevent overfeeding and excess waste.
  • Carbon Source: Add a carbon source (e.g., molasses or cane sugar) to maintain the carbon-to-nitrogen ratio, promoting the growth of beneficial heterotrophic bacteria.

By closely monitoring and managing these parameters, you can maintain a healthy and productive biofloc system for your saltwater shrimp.

 

We learned by reading college research papers like these:

 

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