Biofloc Fish Farming & training

Biofloc fish farming is a technique of improving the quality of water by balancing carbon and nitrogen in the system. Biofloc technology (BFT) is a new and innovative way of fish farming that is cost-effective, environment-friendly and productive. In this article, I will explain every step of the process in detail and provide you with useful information on the varieties of fish to grow, how to take care of them, how to maintain the system and how to feed them.

What is Biofloc?

Biofloc is a term that refers to the aggregation of microorganisms, organic matter and suspended solids in the water. Biofloc is formed by adding a carbon source (such as molasses, wheat bran, rice bran, etc.) and probiotics (such as Bacillus, Lactobacillus, etc.) to the water. The carbon source stimulates the growth of heterotrophic bacteria, which consume the nitrogen waste (such as ammonia and nitrite) produced by the fish and convert it into microbial protein. The probiotics enhance the digestion and immunity of the fish and prevent the growth of harmful pathogens. The biofloc also provides supplemental feed for the fish, as they can graze on it.

What are the Benefits of Biofloc Fish Farming?

Biofloc fish farming has many advantages over conventional open pond fish farming. Some of them are:

• It reduces the dependency on external feed and fish meal, as biofloc provides up to 30% of the protein requirement for the fish.
• It improves the water quality and reduces the water exchange frequency, as biofloc acts as a natural filter and recycles the nutrients in the system.
• It increases the stocking density and productivity of the fish, as biofloc creates a favorable environment for their growth and survival.
• It lowers the production cost and increases the profitability of the fish farming business, as biofloc saves on feed, water, land and labor expenses.
• It minimizes the environmental impact and disease risk of fish farming, as biofloc reduces the waste discharge and prevents the introduction of pathogens into the system.

How to Set Up a Biofloc Fish Farming System?

To set up a biofloc fish farming system, you will need some basic equipment and materials. Here are the steps to follow:

Step 1: Setting up the Pond/Tank

The first thing you need to do is to find a suitable place for your biofloc fish farming system. You can use either an outdoor pond or an indoor tank for this purpose. The size and shape of your pond/tank will depend on your available space, budget and production goal. However, some general guidelines are:

• The pond/tank should be circular or rectangular in shape, with smooth walls and bottom.
• The pond/tank should have a depth of 1.2 to 1.5 meters and a volume of at least 10 cubic meters.
• The pond/tank should have an inlet and outlet for water supply and drainage.
• The pond/tank should have a cover or shade to protect it from direct sunlight, rain and predators.

Step 2: Aeration

The next thing you need to do is to provide adequate aeration for your biofloc fish farming system. Aeration is essential for maintaining dissolved oxygen levels, mixing the water and biofloc particles, and preventing stratification and anaerobic conditions. You can use either mechanical or electrical aerators for this purpose. Some common types of aerators are:

• Paddle wheel aerators: These are devices that have rotating blades that splash water into the air. They are effective for large ponds/tanks with high stocking densities.
• Air diffusers: These are devices that have perforated tubes or plates that release air bubbles into the water. They are suitable for small ponds/tanks with low stocking densities.
• Venturi injectors: These are devices that have nozzles that create a vacuum and suck air into the water stream. They are efficient for medium ponds/tanks with moderate stocking densities.
• The amount and type of aeration you need will depend on your pond/tank size, water quality, fish species and density. However, some general guidelines are:
  • The dissolved oxygen level should be maintained above 4 mg/liter at all times.
  • The water turnover rate should be at least once per hour.
  • The power consumption should be between 0.5 to 1 kilowatt per hour per cubic meter.

Step 3: Selection of Fish Species

The third thing you need to do is to select the appropriate fish species for your biofloc fish farming system. You can choose either freshwater or marine fish species depending on your market demand, climatic conditions and availability of seed. However, some general criteria are:

• The fish species should be fast-growing, hardy and tolerant to high density and low water quality conditions.
• The fish species should be omnivorous or herbivorous, as they can utilize biofloc as a feed source.
• The fish species should have a high market value and consumer preference.

Some examples of suitable fish species for biofloc fish farming are:

• Tilapia: Tilapia is one of the most popular freshwater fish species for biofloc fish farming. It is easy to breed, grow and harvest. It can tolerate low dissolved oxygen levels, high ammonia levels and wide temperature ranges. It can also consume biofloc efficiently. Tilapia has a high demand in both domestic and international markets.
• Catfish: Catfish is another common freshwater fish species for biofloc fish farming. It is resilient to diseases, parasites and predators. It can adapt to various water quality parameters and salinity levels. It can also feed on biofloc effectively. Catfish has a good market potential in many regions.
• Shrimp: Shrimp is one of the most lucrative marine fish species for biofloc fish farming. It has a high growth rate, feed conversion ratio and survival rate. It can thrive in brackish water conditions with minimal water exchange. It can also graze on biofloc readily. Shrimp has a huge demand in both local and global markets.

How to Manage a Biofloc Fish Farming System?

To manage a biofloc fish farming system successfully, you will need to monitor some key parameters regularly and take some necessary actions accordingly. Here are some tips to follow:

Water Quality Management

Water quality is one of the most important factors that affect the performance of your biofloc fish farming system. You will need to measure some parameters such as pH, temperature, salinity, dissolved oxygen, ammonia, nitrite, nitrate and alkalinity on a daily or weekly basis using test kits or meters. You will also need to observe some indicators such as color, clarity, odor and foam on your pond/tank surface.

Some general guidelines for maintaining optimal water quality are:

• pH: The pH level should be between 6.5 to 8.5 for most freshwater fish species and between 7.5 to 8.5 for most marine fish species.
• Temperature: The temperature range should be between 25°C to 32°C for most tropical fish species and between 18°C to 25°C for most temperate fish species.
• Salinity: The salinity level should be between 0 ppt (parts per thousand) to 5 ppt for most freshwater fish species and between 15 ppt to 35 ppt for most marine fish species.
• Dissolved Oxygen: The dissolved oxygen level should be above 4 mg/liter at all times for all fish species.
• Ammonia: The ammonia level should be below 0.5 mg/liter at all times for all fish species.
• Nitrite: The nitrite level should be below 0.1 mg/liter at all times for all fish species.
• Nitrate: The nitrate level should be below 50 mg/liter at all times for all fish species.
• Alkalinity: The alkalinity level should be between 100 mg/liter to 200 mg/liter for most freshwater fish species and between 150 mg/liter to 250 mg/liter for most marine fish species.

To adjust these parameters if they deviate from their optimal ranges, you can use some methods such as:

• Adding lime or sodium bicarbonate to increase pH or alkalinity
• Adding vinegar or hydrochloric acid to decrease pH
• Adding salt or seawater to increase salinity
• Adding freshwater or rainwater to decrease salinity
• Increasing aeration or water exchange to increase dissolved oxygen
• Decreasing feeding rate or stocking density to decrease ammonia or nitrite
• Adding nitrifying bacteria or plants to reduce nitrate

Biofloc Management

Biofloc management is another crucial aspect that affects the efficiency of your biofloc fish farming system. You will need to control some factors such as carbon source type, carbon/nitrogen ratio (C/N), probiotic type, probiotic dosage, biofloc size, biofloc concentration and biofloc harvesting.

Some general guidelines for managing optimal biofloc conditions are:

Carbon Source Type: You can use various organic materials such as molasses, wheat bran, rice bran, corn starch, cassava starch, sugar cane bagasse, etc., as carbon sources for your biofloc system. However, some factors such as availability, cost, solubility, degradability and palatability and C/N ratio should be considered when choosing a carbon source for your biofloc system. However, some common carbon sources that have been used successfully are:

• Molasses: Molasses is a by-product of sugar cane processing. It is a cheap, available and soluble carbon source that can stimulate biofloc formation quickly. However, it can also cause rapid pH fluctuations and bacterial blooms if added excessively. The recommended dosage of molasses is 1 to 2 grams per liter per day1.
• Wheat Bran: Wheat bran is a by-product of wheat milling. It is a low-cost, accessible and degradable carbon source that can support biofloc growth steadily. However, it can also cause water turbidity and sedimentation if added excessively. The recommended dosage of wheat bran is 2 to 3 grams per liter per day1.
• Rice Bran: Rice bran is a by-product of rice milling. It is a cheap, available and degradable carbon source that can enhance biofloc production gradually. However, it can also cause water cloudiness and sludge accumulation if added excessively. The recommended dosage of rice bran is 2 to 3 grams per liter per day1.
• Carbon/Nitrogen Ratio (C/N): The C/N ratio is the ratio of the amount of carbon to the amount of nitrogen in the water. It is an important factor that determines the efficiency of biofloc formation and utilization. A high C/N ratio favors the growth of heterotrophic bacteria and biofloc production, while a low C/N ratio favors the growth of nitrifying bacteria and nitrate accumulation. The optimal C/N ratio for biofloc fish farming is between 10:1 to 20:12. You can adjust the C/N ratio by adding more or less carbon source or feed according to your water quality test results.
• Probiotic Type: Probiotics are beneficial microorganisms that can improve the digestion and immunity of the fish and prevent the growth of harmful pathogens in the water. You can use various types of probiotics for your biofloc fish farming system, such as Bacillus, Lactobacillus, Nitrobacter, Nitrosomonas, etc. However, some factors such as compatibility, viability, dosage and frequency should be considered when choosing a probiotic type for your biofloc system. However, some common probiotics that have been used successfully are:
• Bacillus: Bacillus is a genus of gram-positive, rod-shaped bacteria that can produce enzymes and antibiotics. It can degrade organic matter, reduce ammonia and nitrite levels, enhance biofloc formation and quality, and inhibit pathogenic bacteria in the water. The recommended dosage of Bacillus is 106 to 108 colony forming units (CFU) per liter per week1.
• Lactobacillus: Lactobacillus is a genus of gram-positive, lactic acid-producing bacteria that can improve the intestinal health and immunity of the fish. It can also lower pH and nitrate levels, increase biofloc stability and palatability, and suppress pathogenic bacteria in the water. The recommended dosage of Lactobacillus is 106 to 108 CFU per liter per week1.
• Probiotic Dosage: The probiotic dosage is the amount of probiotics that you add to your biofloc fish farming system. It depends on your pond/tank size, water quality, fish species and density. You should follow the manufacturer’s instructions or consult an expert when applying probiotics to your biofloc system. However, some general guidelines are:
  • The probiotic dosage should be sufficient to maintain a healthy microbial balance in the water.
  • The probiotic dosage should be adjusted according to the water quality test results and fish health condition.
  • The probiotic dosage should be applied regularly and evenly throughout the pond/tank.
• Biofloc Size: The biofloc size is the diameter of the biofloc particles in the water. It affects the settling rate, suspension rate, grazing rate and digestibility of the biofloc by the fish. A small biofloc size (<0.5 mm) has a high settling rate, low suspension rate, high grazing rate and high digestibility by the fish. A large biofloc size (>1 mm) has a low settling rate, high suspension rate, low grazing rate and low digestibility by the fish. The optimal biofloc size for biofloc fish farming is between 0.5 mm to 1 mm2. You can control the biofloc size by adjusting the aeration intensity, carbon source type and dosage, probiotic type and dosage and biofloc harvesting frequency.
• Biofloc Concentration: The biofloc concentration is the amount of biofloc particles in the water. It affects the water clarity, oxygen demand, nutrient availability and fish health. A high biofloc concentration (>500 mg/liter) has a low water clarity, high oxygen demand, high nutrient availability and low fish health. A low biofloc concentration (<100 mg/liter) has a high water clarity, low oxygen demand, low nutrient availability and high fish health. The optimal biofloc concentration for biofloc fish farming is between 100 mg/liter to 500 mg/liter1. You can measure the biofloc concentration by using a Secchi disk or a turbidity meter.
• Biofloc Harvesting: Biofloc harvesting is the process of removing excess biofloc particles from the water. It is necessary to maintain the optimal biofloc concentration and quality in the system. You can harvest biofloc by using some methods such as:
• Settling: Settling is a method of allowing the biofloc particles to settle at the bottom of the pond/tank by reducing the aeration intensity or stopping it completely. Then, you can siphon or drain out the settled biofloc from the bottom outlet. This method is simple and cheap, but it can also cause oxygen depletion and stress for the fish.
• Filtration: Filtration is a method of passing the water through a filter media (such as sand, gravel, cloth, etc.) that can trap the biofloc particles. Then, you can collect and dispose of the filtered biofloc from the filter media. This method is effective and safe, but it can also be expensive and labor-intensive.
• Centrifugation: Centrifugation is a method of spinning the water at a high speed in a centrifuge device that can separate the biofloc particles from the water by their density difference. Then, you can collect and dispose of the separated biofloc from the centrifuge device. This method is efficient and fast, but it can also be costly and complex.

How to Feed and Harvest Fish in a Biofloc Fish Farming System?

To feed and harvest fish in a biofloc fish farming system, you will need to follow some best practices and precautions. Here are some tips to follow:

Feeding Management

Feeding management is an important aspect that affects the growth, health and profitability of your fish in a biofloc fish farming system. You will need to consider some factors such as feed type, feed quality, feed quantity, feed frequency and feed distribution.

Some general guidelines for feeding management are:

• Feed Type: You can use various types of feed for your fish in a biofloc fish farming system, such as commercial pellets, homemade feed, natural feed or biofloc itself. However, some factors such as nutritional value, stability, palatability and cost should be considered when choosing a feed type for your fish. However, some common feed types that have been used successfully are:
• Commercial Pellets: Commercial pellets are ready-made feed that are formulated with various ingredients (such as fish meal, soybean meal, corn, vitamins, minerals, etc.) to meet the nutritional requirements of your fish species. They are convenient, consistent and easy to use. However, they are also expensive, dependent on external sources and may contain unwanted additives or contaminants.
• Homemade Feed: Homemade feed are self-made feed that are prepared with locally available ingredients (such as rice bran, wheat bran, oil cake, fish waste, etc.) to suit your fish species. They are cheap, independent and adaptable. However, they are also laborious, variable and difficult to store or transport.
• Natural Feed: Natural feed are live or fresh feed that are obtained from natural sources (such as plankton, worms, insects, etc.) to supplement your fish diet. They are nutritious, attractive and beneficial. However, they are also scarce, seasonal and risky (as they may carry diseases or parasites).
• Biofloc: Biofloc is an alternative or supplemental feed that is produced in situ in your biofloc fish farming system. It is protein-rich, available and sustainable. However, it is also variable, unbalanced and limited (as it depends on your water quality and carbon source).
• Feed Quality: The feed quality is the nutritional value and physical condition of your feed for your fish in a biofloc fish farming system. It affects the growth rate, feed conversion ratio, survival rate and health status of your fish. You should ensure that your feed quality is high by following some measures such as:
  • Checking the label or analysis report of your feed for its ingredients, composition, expiry date and storage conditions.
  • Storing your feed properly in a cool, dry and dark place away from moisture, heat and pests.
  • Using your feed within its shelf life or before it deteriorates or spoils.
  • Discarding any damaged, moldy or contaminated feed immediately.
• Feed Quantity: The feed quantity is the amount of feed that you provide for your fish in a biofloc fish farming system. It affects the growth performance, water quality and economic efficiency of your system. You should adjust your feed quantity according to your fish species, size, density, appetite and condition. However, some general guidelines are:
  • The daily feed quantity should be between 1% to 5% of your total fish biomass depending on their growth stage.
  • The daily feed quantity should be divided into 2 to 4 equal portions depending on their feeding habits.
  • The daily feed quantity should be reduced or increased based on their feeding response or behavior.

• Feed Frequency: The feed frequency is the number of times that you provide feed for your fish in a biofloc fish farming system per day. It affects the digestion efficiency, nutrient utilization and waste production of your fish. You should determine your feed frequency based on your fish species, size, activity and preference. However, some general guidelines are:
  • The daily feed frequency should be between 2 to 4 times per day depending on their feeding habits.
  • The daily feed frequency should be consistent and regular throughout the culture period.
  • The daily feed frequency should be synchronized with their natural feeding rhythms (such as dawn or dusk).
• Feed Distribution: The feed distribution is the manner and method that you provide feed for your fish in a biofloc fish farming system. It affects the feeding accessibility, uniformity and competition of your fish. You should ensure that your feed distribution is adequate and fair by following some methods such as:
  • Spreading your feed evenly over the entire pond/tank surface using a scoop or a feeder device.
  • Broadcasting your feed manually or automatically using a blower or a sprayer device.
  • Sinking your feed slowly or rapidly using a pelletizer or an extruder device.

Harvesting Management

Harvesting management is an essential aspect that affects the quality, quantity and profitability of your fish in a biofloc fish farming system. You will need to consider some factors such as harvesting time, harvesting method
and harvesting equipment.

Some general guidelines for harvesting management are:

• Harvesting Time: The harvesting time is the period that you decide to harvest your fish in a biofloc fish farming system. It depends on your market demand, fish size, growth rate and condition. You should plan your harvesting time carefully by following some measures such as:
  • Monitoring your fish growth and health regularly using a scale or a sample net.
  • Estimating your fish biomass and production using a formula or a software.
  • Comparing your fish size and quality with the market standards and preferences.
  • Scheduling your harvesting time according to the market demand and price.
• Harvesting Method: The harvesting method is the way that you collect your fish from a biofloc fish farming system. It affects the harvesting efficiency, labor requirement and fish quality. You should choose your harvesting method wisely by following some methods such as:
  • Draining: Draining is a method of emptying the water from your pond/tank completely or partially using a pump or a valve. Then, you can catch your fish easily using a net or a basket. This method is simple and fast, but it can also cause water loss and stress for the fish.
  • Seining: Seining is a method of pulling a large net across your pond/tank horizontally or vertically. Then, you can lift your fish out of the water using the net. This method is effective and gentle, but it can also be expensive and labor-intensive.
  • Trapping: Trapping is a method of placing a device (such as a cage, a trap or a funnel) in your pond/tank that can attract and retain your fish inside. Then, you can remove your fish from the device using a net or a basket. This method is selective and convenient, but it can also be time-consuming and risky (as it may damage or escape the fish).
• Harvesting Equipment: The harvesting equipment is the tool or machine that you use to harvest your fish from a biofloc fish farming system. It affects the harvesting speed, safety and quality. You should use your harvesting equipment properly by following some tips such as:
  • Choosing the right size, shape and material of your harvesting equipment according to your fish species, size and quantity.
  • Cleaning and sanitizing your harvesting equipment before and after each use to prevent contamination or infection.
  • Handling and transporting your harvesting equipment carefully to avoid damage or injury.

Conclusion

Biofloc fish farming is a promising technique of improving the water quality and productivity of aquaculture systems. It has many benefits such as reducing feed cost, water exchange frequency, environmental impact and disease risk. It also has some challenges such as maintaining optimal water quality, biofloc concentration and quality, feeding management and harvesting management. By following this guide, you can learn the basic steps of setting up, managing, feeding and harvesting a biofloc fish farming system successfully.

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