Introduction: The Biofloc technology is to solve the problems of water pollution and improve the use of water resources, and recycling the nutrients found in the water by a community of heterotrophic bacteria. This Biofloc system has allowed aquaculture farms to reduce and sometimes eliminate water exchange, though providing added value through the products resulting from microbial metabolism.
A guide to Biofloc Technology (BFT) In Aquaculture in India
Biofloc technology (BFT) can be explained as an innovative and affordable technology designed to enhance environmental control over fish production. This system converts toxic materials including ammonia, nitrite, and nitrate into a useful product called proteinaceous feed. When there are highly restricted water exchange problems under high stocking fish density ponds or tanks, this is the most efficient technology to be implemented for maintaining optimal quality, productivity, biosecurity, and sustainability.
In aquaculture, the “Biofloc” technology acts as a retention strap for the nutrients in the pond and reduces maintenance costs. Because, it can be used as food supplement for the commercial organisms being cultured, which provides an added value by improving the food consumption rate.
The “Biofloc” system applies to a compound made out of 60 to 70% of organic matter, which includes a heterogeneous mixture of microorganisms that are fungus, algae, and rotifers and of 30 to 40% of inorganic matter such as colloids, organic polymers, and dead cells.
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Water preparation in Biofloc
Water Preparation in Biofloc is the main important to start fish farming using the Biofloc system.
Prepare water in Biofloc
To prepare water in a fish tank you need to follow given points;
- Wash Pond Cleanly
- Fill the tank approx 50% of their capacity
- Start aeration
- Add Salt, Caco3, Probiotic
Wash Pond Cleanly – First clean tank to start water preparation. If you are the first time using pond or doing in already used the tank in both case wash tank. This we are doing to prevent the tank from harmful bacteria.
Fill the tank approx 50% of their capacity – After washing the tank start filling water in a fish tank. Fill water tank approximately 35-50% by freshwater. Don’t fill more than this because bacteria require a certain environment to grow.
Start aeration – Start aeration to mix oxygen with water. Fish require oxygen and during aeration, we flow oxygen through pumps. So start aeration to prepare water in the Biofloc system.
Add Salt, Caco3, and Probiotic – Now it is the main important part of Water Preparation in the Biofloc system. First, we need to add 1 kg salt per 10000 L of water. Salt helps water to maintain TDS (total dissolved solids) and also help fish in strain. Now Add Calcium Carbonate or Caco3 in water.
Add Probiotic in water – Probiotic is a type of supplement that contains bacteria that convert the waste in protein food for fish.
The suitable culture species for the Biofloc system
A necessary factor in designing a Biofloc system is the species to be cultured. Biofloc systems work best with species that can derive some nutritional advantage from the direct consumption of floc. Biofloc systems are most suitable for species that can tolerate high solids concentration in water and generally tolerant of poor water quality.
Some fish species such as tilapia have physiological adaptations that allow them to consume Biofloc and digest microbial protein and taking advantage of the Biofloc system as a food resource. Nearly all Biofloc systems are used to grow tilapia or carps. Catfish and hybrid striped bass are not good fish species for Biofloc technology because they do not tolerate water with high solids concentrations.
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The fundamental idea behind Biofloc system
Biofloc system keeps high water quality and growth rate. Biofloc system achieves high Carbon-Nitrogen balance through the inclusion of carbohydrate and it enhances the water quality by producing single-cell microbial protein. When such an atmosphere is created, the development of dense microorganisms takes place and they work as a protein food source with the bioreactor that regulates water quality. This situation makes an ideal setting for the fish to thrive in an effective and fast manner.
The fundamental idea behind the Biofloc system is the procedure of generating the nitrogen cycle by sustaining a better Carbon and Nitrogen ratio. It is being achieved through the stimulation of heterotrophic microbial growth, which absorbs the nitrogenous waste, and the cultured species create use of this waste as a feed. Fish farmers should realize the fact that Biofloc technology is not only highly efficient in addressing the waste but provides much-needed nutrition to the fish.
The Biofloc technology is one of the innovative techniques used in fish farming which results in a great production of fishes. Biofloc system is defined as macroaggregates of organic matters contain bacteria algae, rotifers, and remains of dead organisms, microalgae, fecal pellets, and other invertebrates.
The Biofloc production systems for aquaculture
Biofloc production systems were developed to improve environmental control over production. In places where water is scarce, more intensive forms of aquaculture must be practiced for cost-effective production. High-density rearing of fish normally wants some waste treatment infrastructure.
The Biofloc system technology was developed to prevent the introduction of disease to a farm from incoming water. In the past, standard operation of fish ponds included water exchange (typically 10 percent per day) as a method to control water quality. In estuarine areas with many fish farms practicing water exchange, the disease would spread among farms. Reducing water exchange is an obvious strategy for improving fish farm biosecurity. Fish farming began moving toward more closed and intensive production where waste treatment is more internalized.
Applications of Biofloc technology (BFT) in aquaculture
The Biofloc technology (BFT) is an environmentally friendly aquaculture technique based on microorganism production. Fish are grown intensively (minimum of 300 g of biomass per square meter) with zero or minimum water exchange. Also, continuously water movement in the entire water column is required to induce the macro aggregate or Biofloc formation. Nutrients in water (by a known carbon-to-nitrogen ratio of 12–20:1) will give naturally to a heterotrophic microbial community formation and stabilization.
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These microorganisms play three major roles they are
- Maintenance of water quality, by the uptake of nitrogen compounds generating in microbial protein;
- Nutrition, increasing culture feasibility by reducing feed conversion ratio (FCR) and a decrease of feed costs; and
- Competition with pathogens.
The culture of Biofloc technology
The wastewater from the fish culture system was used for the culture of the Biofloc system. Fishes at the fingerling stage were collected from the nearby fish farm and acclimatized for 10 to 15 days during which they were fed with a good quality diet. After this, the fingerlings were removed and stocked in the troughs of 50-liter capacity and kept under laboratory conditions. Continuous aeration was given by air pumps. No water exchange was completed and the excreta and uneaten feed were allowed to accumulate in the water.
Different physicochemical parameters like DO, FCO2, temperature, pH, and ammonia were measured from time to time using standard methods. When the level of total ammonia nitrogen exceeded 1.0 mg/l the fishes were removed from the trough and that water was used for the culture of the Biofloc system.
Cow dung and pond soil were added to the water in order its increase the nutritional quality and growth of bacteria respectively. Carbohydrate source that means molasses was also added to the culture water. After the addition of molasses and provide continuous aeration, the froth appeared within 3 days which later on turned brownish.
During the subsequent days, froth disappeared and very small suspended particles started appearing in the water column. A drop of suspension when observed under the microscope was found to have protozoan like paramecium, diatoms along with colonies of bacteria.
The composition and nutritional value of Biofloc
Biofloc is a heterogeneous aggregate of suspended particles and different varieties of microorganisms associated with extracellular polymeric substances. It is composed of microorganisms for example bacteria, algae, fungi, invertebrates, and detritus, etc. It is a protein-rich live feed produced as a result of the conversion of unused feed and excreta into a natural food in a culture system on exposure to sunlight. Each floc is held together in a loose matrix of mucus that is secreted by bacteria and bound by filamentous microorganisms.
A good nutritional value is found in the Biofloc system. The dry weight protein ranges from 25 – 50 percent, fat ranges from 0.5 to 15 percent. It is an excellent source of vitamins and minerals, particularly phosphorus. It affects similar to probiotics. The dried Biofloc is proposed as an ingredient to replace with the fishmeal or soybean in the feed. The nutritional quality is very good; however, only limited qualities are available.
The benefits of Biofloc technology
Some of the benefits of Biofloc system are given below;
- First and foremost, the Biofloc system is an eco-friendly culture system and the environmental impact can be reduced significantly. As a fish farmer, you do not have to worry too much about water exchange because this Biofloc system demands minimal or limited water exchange. Since this process improves the fish survival rate, feed conversion, and growth performance; you can expect optimal productivity.
- Another benefit is the improved bio-security and you can efficiently prevent the risks associated with dangerous pathogens and water pollution.
- The BFT reduces the use of protein-rich feed and the expenses involved with standard feed. Hence, you can explain it as a technology that promotes cost-effective feed production. The Biofloc system or BFT reduces the pressure on capture fisheries, you do not have to overly depend on trash fish or cheaper fish for preparing the fish feed.
- Environmental impact reduces.
- Efficiently improves land and water use.
- Negligible or zero water exchange.
- Productivity is high in BFT (enhances survival rate, growth performance, feed conversion in the culture systems of fish).
- BFT reduces water pollution and the risk of introduction and spread of pathogens.
- The Biofloc technology reduces the utilization of protein-rich feed and the cost of standard feed.
Disadvantages of Biofloc technology
- Energy requirement for mixing and aeration increases.
- Reduced response time due to water respiration rates is elevated.
- The start-up period required.
- Alkaline supplement required.
- Pollution potential from nitrate accumulation increases.
- Seasonal and inconsistent performance for sunlight-exposed systems.
The cost of Biofloc fish tank and Biofloc farm investment cost
The cost of Biofloc tank for fish farming is approximately Rs 10,000/piece.
The cost of Biofloc farm investment will be approximately Rs.14 lakh per hectare.
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