Bio floc technology is natural and biological method of fish farming which maintains water quality and provide feed to the cultured fish species in the pond or tank. It is highly innovative technique developed recently from Philippines and get popular all over the world very quickly. It is also getting very popular in Nepal where it is mainly being practiced in urban areas like Kathmandu and Chitwan.
Now, let`s discuss what is bio floc, nutritional composition, benefits and disadvantages of bio floc technology.
Need of Bio floc Technology:
As fish farming is very popular commercial farming in world, bio floc is innovative as well as cost effective/minimizing technique where nitrogenous wastes such as nitrate, nitrite and ammonia which are toxic to fish and primary material for water pollution in pond, are converted into proteinaceous feed decomposed by microorganisms. This technique utilizes very less water or limits the wastage of water in pond, allow for high stock density, good aeration and promising growth of biota in the pond/tank.
We are familiar that, among the total cost of production, 70% cost of production is only for maintaining feed to the fish species and the principle of bio floc is to optimize FCR (Feed Conversion Ratio) and reduce cost of feed in the production system. Similarly, it also uses the principle of minimum water wastage or zero water exchange status. In this technique, higher ratio of C:N is maintained in the pond by supplementing extra carbohydrate source in to the fish in the tank/pond which provide feed to heterotrophic microbial growth which eventually converts the nitrogenous waste into proteinaceous microbial cell which are available to the fish species in the tanks/ponds.
This technique has been adopted to shrimp farming and Nile tilapia which are very good responsive to high density stocking.
Bio floc is composed of bacteria, fungi, algae, detritus and other invertebrates which are the nutritional source to the fish. The excreta waste of fishes are converted into proteinaceous microbial cell in the pond. The microorganisms act as bioreactor and source of feed to the aquatic living. Sunlight is very necessary component in this system. Each floc is held together by mucilaginous secretions of bacteria in a loose matrix. Flocs may be of different size where small sized flocs are microscopic in nature but large flocs ae quite visible with naked eyes too. Nutritional value of bio floc is very promising which consists of 25-50% protein, 0.5-15% fat in dry weight, vitamins, minerals and phosphorus. Addition of carbohydrate in form of molasses is necessary to maintain high C:N ratio which is food source to the microorganisms to assimilate the nitrogenous wastes into bio floc.
Most commonly, this technique is practiced in Urban areas in the fish tank / circular pond to accommodate higher density of fish species.
Following process should be followed before starting your bio floc fish farm.
Circular tanks either of cement, stainless steel or tarpaulin can be used for this purpose. Depth of tank essential is 3.5-4 feet and volume of tank is calculated with formula of cylinder i.e. V = ℿR2H *1000.
ℿ = 3.14
R = radius of tank
H = height of tank
V = volume of cylinder in liters
Circular tank is necessary so fish can move around the tank that helps in faster growth.
Fill the tank with water and check the pH level as well as total dissolved salts. Maintain pH between 7.5 – 8 and TDS in range of 1400 – 166. For acidic condition add lime to mend the pH of water. Aeration to tank is essential for complete mixing in case of salt addition to increase TDS. Add probiotic of 2 gram only after one day per 100 liters water and mix 10 grams of molasses per 100 liters of water where it takes around 7 days to form floc.
Fish seed disinfecting with potassium permanganate for about 30 seconds to make them disease free. After they are kept in saline water for 30 minutes by then they will be ready for stocking in the tank.
Add CaCo3 in case pH decreases to maintain pH of water. Carbon sources such as molasses are added to decrease ammonia amount in the tank after fish stocking is done. Aerator should be used to maintain oxygen amount in the water for better performance of fish in tank.
Benefits of Bio floc Technology:
Bio floc is very promising method of fish farming for lesser FCR and substitute for fish feed, optimum utilization of water. It is in fact a boon to fish farming farmers all over world. Most benefits are mentioned below: –
- It is environment friendly fish culture system.
- Water pollution which causes environmental impacts is minimized to almost zero.
- It requires very small land area. So, it makes high land use efficiency.
- Feed required is minimum in this technique so, less FCR and low feed cost.
- Water use efficiency is also high i.e. zero water exchange.
- Enhanced growth performance, survival rate in the culture system.
- It reduces the biosecurity problem and pest and disease pathogen attacking fish.
Disadvantages of Bio-floc fish farming:
Despite of having several advantages, bio floc technique is quite lacking some aspects to meet the conventional fish farming system. We all are well known that every technology has their both good and bad aspects and here are some bad aspects of bio floc technology: –
- Aeration is very essential component of bio floc system, which is quite expensive and adds extra expenses than the conventional system as it requires higher energy requirement.
- Similarly, sunlight is another requirement in this technique which makes this only seasonal performance and very inconsistent.
- There may be chance of nitrate accumulation for further pollution in the pond.
Learn more about Bio Floc Fish Farming Technology in Nepal here. https://www.nepjol.info/index.php/IJASBT/article/view/28933