FISH FARMING THROUGH BIOFLOCK TECHNOLOGY (BFT) IN INDIA
Compiled & shared by-DR. RAJESH KUMAR SINGH, (LIVESTOCK & POULTRY CONSULTANT), JAMSHEDPUR, JHARKHAND,INDIA 9431309542, rajeshsinghvet@gmail.com
& Er Ritesh pandey, Rohtas, Bihar (Fishery entrepreneur),JAGO KISAN JAGO
Increasing trends of human population from 1.5 to 6.4 billion and is predicted to increase to 9 billion by the 2050 necessitates the production diversification to reduce the malnourishment, which has been estimated 840 million. To ensure the health of world population by providing nutritionally balanced especially protein rich food, animal husbandry and fisheries are the two sources of animal protein. Fish and fishery products are the safest group of animal protein, containing all essential amino acids, essential fatty acids of n-3, n-6 series . But today’s production and demand have a huge gap compared to the exponential growth of world population. To solve these problems culture of organisms under controlled conditions in water ie; aquaculture is the only way. But in aquaculture intensification is necessary to meet the food demand.
In aquaculture, the major cost during the whole production cycle has been contributed by feeding of fish. Similarly, about 60-70% of the variable cost involved in the operation were attributed to feed alone which in turn reduced the farmer’s profit (Gabriel et al., 2007). Erondu et al., (2006) noted that the principal factor which affects the development and expansion of the aquaculture industry is nothing but the cost of feed. Another major issue raised in today’s situation is water scarcity which severely ruins food security and hampers the development of the sector. Almost 70 percent of all water removal were accounted from agriculture which became a significant cause of water scarcity. It was reported that approximately 2,000 to 5,000 liters of water are required to produce the food consumed by one person daily (www.fao.org). These issues can be overcome by increasing the fish biomass per unit area and reducing the use of expensive feed ingredients or high protein feeds. When fish fed with high protein diets, the nitrogen (appr. 70 %) present in protein is discharged as waste into the surrounding culture water. This waste nitrogen can be incorporated into a functional form by the culture species in biofloc technology. By using biofloc technology as a culture system, two problems can be solved at once, i.e., reduction of protein inputs and elimination of water exchange to maintain water quality. Microbial floc not only helps to improve the environmental control over production by reducing the nitrogen and ammonia from the culture water but also act as nutrient trappers who can be useful in the feed management thereby reducing the feed cost. They are also helpful in enhancing the biosecurity and health. The BFT is achievable by using different types of organic carbon. Utilization of low-value carbohydrates for the production of biofloc can further reduce the cost of production in aquaculture. The use of Biofloc technology in commercial aquaculture is insufficient, and this technique is not yet fully standardized. Nowadays, milkfish farming becomes a major aquaculture venture in the coastal states of India. As the problem arises in the shrimp industry, the fish farmer gains more interest towards the culture of brackish water fishes like milkfish, mullet, etc. due to their higher prices in the market. Milkfish get a high price of Rs. 150 per kg in the local markets of many coastal states like Kerala, Andhra Pradesh, Tamilnadu, etc. But some constraints like technical, social, economic, and environmental problems hamper the milkfish production .Fish farmers should be skilled to practice intensive fertilization and extensive feeding in ponds. The high-priced imported inorganic fertilizers and commercial feeds restricted the improvement of technology. The major economic constraints existing in the cultural practices are the high capital and the high cost of credit. Generally, the farmers should know the productive and recent technology which can provide high economic returns compare to the traditional practices. Likewise, the rearing of fry to fingerling stage and their trade can provide more value and economic return to the farmers with less capital investment by using biofloc technology. Before initiating such kind of commercially intensive milkfish fingerling production units, its economic viability and feasibility need to be tested.
Issues in aquaculture ——
The aquaculture industry is growing fast at a rate of 9% per year since 1970’s, but is going through unsustainability in the meaning of environmentally and economically, haunted by number of environmental and social issues .Over usage of antibiotics, disease and exotic fish transfer to wild and omitting of heavy load nutrients are under consideration. Over dependence of fish meal and privatization of public common leads to physical conflicts among fishermen and depletion of natural resources. All these factors searches opportunities for economic and environmental developments permeate in to many facets of the industry[8]. Of the total production expenses 50% represents for feed cost, which is predominantly due to the cost of protein component in commercial diet[9]For the production of 1 kg live weight fish needs 1-3 kg dry wt feed( FCR is about 1-3, . Of the total nitrogen input in culture ponds only 20-30% retain in biomass and the rest becomes a polluting agent of the water by producing high level toxicants such as ammonia and nitrite leads to eutrophication in the surrounding water of the aquaculture farms . Approximately 36% of feed excreted as in the form of organic waste. Thus tool to make up industry more sustainable pond management should be geared towards improving nutrient retention.
Biofloc Technology——-
Now a days closed aquaculture systems are more safe for biosecurity, having environmental and marketing advantages over conventional extensive and semi intensive systems . Due to the re usage of water reduces introduction of pathogens and exotic to the external environment. Such a type of environment friendly technology for closed aquaculture is Biofloc Technology(BFT). More nutrient retention and recycling has been take place internally without so more cost compared to the conventional waste management technologies such as recirculating aquaculture systems and biofiltration, both needs complex internal filtration, expensive, laborious and economically not feasible. BFT is an innovative one, from conventional autotrophic to autotrophic- heterotrophic system. Microbes like bacteria are generally regarded as a disease causing agent in animal and plants. But in controlled conditions dense and active aerobic microbial communities control water qualities through immobilization of toxic metabolites to microbial protein and recycle the feed residue and raise the feed efficiency . Compared to the conventional photoautotrophic system BFT has more advantages such as diurnal variation of dissolved oxygen and hydrogen ion concentration is limited. Assimilation of inorganic nutrients through bacteria in suspension is an additional protein source than the biosynthesis of algae. Through the decomposition of organic matter by microorganisms leads to the production of new bacterial cell amounting 40-60% of the metabolized organic matter. This aerobic decomposition can be higher in high C/N ratio (through the addition carbohydrate source should be economically feasible) with high oxygenic conditions. BFT is a green approach in aquaculture knowing in different names such as zero exchange autotrophic- heterotrophic system active sludge or suspended bacterial based system , Single cell protein production system, Microbial floc system etc. Now biofloc has been focused internally as an alternative protein for fish meal, mainly produced in the form of microbial meal. Many researchers has been conducted the study of nutritional acceptability of biofloc.
It is an innovative and cost-effective technology in which toxic materials to the fish and shellfish such as Nitrate, Nitrite, Ammonia can be converted to useful product, ie., proteinaceous feed. It is the technology used in aquaculture system with limited or zero water exchange under high stocking density, strong aeration and biota formed by biofloc.The culture of biofloc will be productive in the case of culture tanks exposed to sun.
Biofloc technology application offers benefits in improving aquaculture production that could contribute to the achievement of sustainable development goals. This technology could result in higher productivity with less impact to the environment. Furthermore, biofloc systems may be developed and performed in integration with other food production, thus promoting productive integrated systems, aiming at producing more food and feed from the same area of land with fewer input. The biofloc technology is still in its infant stage. A lot more research is needed to optimize the system (in relation to operational parameters) e.g. in relation to nutrient recycling, MAMP production and immunological effects
Biofloc system – the need————-
Biofloc system was developed to improve the environmental control over the aquatic animal production. In aquaculture, the strong influential factors are the feed cost (accounting to 60% of the total production cost) and most limiting factor is the water/land availability. High stocking density and rearing of aquatic animals requires wastewater treatment. Biofloc system is a wastewater treatment which has gained vital importance as an approach in aquaculture.
The principle of this technique is the generation of nitrogen cycle by maintaining higher C: N ratio through stimulating heterotrophic microbial growth, which assimilates the nitrogenous waste that can be exploited by the cultured spices as a feed. The biofloc technology is not only effective in treating the waste but also grants nutrition to the aquatic animal.
The higher C : N is maintained through the addition of carbohydrate source (molasses) and the water quality is improved through the production of high quality single cell microbial protein. In such condition, dense microorganisms develop and function both as bioreactor controlling water quality and protein food source. Immobilization of toxic nitrogen species occurs more rapidly in bioflocs because the growth rate and microbial production per unit substrate of heterotrophs are ten-times greater than that of the autotrophic nitrifying bacteria. This technology is based on the principle of flocculation within the system.
The biofloc technology has been implemented in shrimp farming due to its bottom dwelling habit and resistance to environmental changes. Studies have been conducted to assess the larval growth and reproductive performance of shrimps and Nile tilapia. An improved breeding performance was observed in shrimp reared in the biofloc system when compared to that of normal culture practices. Similarly improved larval growth performance was also noticed.
Composition and nutritional value of biofloc——–
Biofloc is a heterogeneous aggregate of suspended particles and variety of microorganisms associated with extracellular polymeric substances. It is composed of microorganisms such as bacteria, algae, fungi, invertebrates and detritus, etc. It is a protein-rich live feed formed as a result of 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 or electrostatic attraction. Large flocs can be seen with the naked eye, but most of them are microscopic. Floc size range from 50 – 200 microns.
A good nutritional value is found in biofloc. The dry weight protein ranges from 25 – 50 percent, fat ranges 0.5 – 15 percent. It is a good source of vitamins and minerals, particularly phosphorous. It also has an effect similar to probiotics. The dried biofloc is proposed as an ingredient to replace the fishmeal or soybean in the feed. The nutritional quality is good; however, only limited qualities are available. Furthermore, the cost-effectiveness of producing and drying biofloc solids at a commercial scale is a challenge.
Benefits of Biofloc culture system————
• Eco-friendly culture system.
• It reduces environmental impact.
• Improves land and water use efficiency
• Limited or zero water exchange
• Higher productivity (It enhances survival rate, growth performance, feed conversion in the culture systems of fish).
• Higher biosecurity.
• Reduces water pollution and the risk of introduction and spread of pathogens
• Cost-effective feed production.
• It reduces utilization of protein rich feed and cost of standard feed.
• It reduces the pressure on capture fisheries ie., use of cheaper food fish and trash fish for fish feed formulation.
Disadvantages of Biofloc Technology————-
• Increased energy requirement for mixing and aeration
• Reduced response time because water respiration rates are elevated
• Start-up period required
• Alkalinity supplementation required
• Increased pollution potential from nitrate accumulation
• Inconsistent and seasonal performance for sunlight-exposed systems
