Potential Scope, Advantages, and Challenges of RAS and Bio-floc Technology in Indian Fish Farming

Potential Scope, Advantages, and Challenges of RAS and Bio-floc Technology in Indian Fish Farming

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  1 Potential Scope, Advantages,and Challenges of Recirculating Aquaculture Systems (RAS) and Bio-floc Technology (BFT) in Fish Farming in the Indian Scenario By B. Bhaskar, (Fisheries) 1. Introduction Global population is exponentially increased over 8 billion, another side climate change, natural disasters, anthropogenic drivers impact also significantly raised over the years in agri- aqua production system, resulted in desertification, However this unproductive land also can be utilized for aquaculture including for promotion of RAS & Biofloc technology. 2. Strength of Indian Fisheries Sector: India’s fisheries and aquaculture sector has rapidly evolved into a 198 lakh metric tonne powerhouse during 2025-26 (Dept. of Fisheries, GOI, 2026). Global Standing: India contributes roughly 9% of the world's aquatic animals and holds the globally 1st in inland fisheries, 2nd rank in Aquaculture production. Record Exports and Trade India exported 19,72,018 metric tonnes (MT) of seafood valued at ₹73,890.46 crore (USD 8.46 billion) during FY 2025–26, registering an all-time high in both volume and value despite challenging global market conditions Global Reach: India exports over 350 seafood products to >130 countries, with aquaculture comprising 62% of the export value 3. RAS& Bio-flocs: Global aquaculture must expand to meet rising protein demands sustainably. Traditional open- pond systems face strict limitations due to heavy land use, water scarcity, and environmental runoff risks. Modern producers lean heavily on Recirculating Aquaculture Systems (RAS) and Biofloc Technology (BFT) to maximize yield while conserving natural resources. Recirculating Aquaculture Systems (RAS) and Biofloc Technology (BFT) represent two highly intensive, controlled, and sustainable methods of aquaculture. While RAS relies on mechanical and biological filtration, BFT utilizes beneficial bacteria suspended in the water to convert waste into natural feed RAS comes equipped with an external filter that removes bacteria that produce nitrogen, as well as larger solids from the tank system. Most RAS also include ultraviolet lamps that sterilize the water so that no unwanted bacteria will infect your fish. Unfortunately, recirculating aquaculture systems tend to be more expensive than Biofloc. Biofloc systems use an extensive microbial community to remove unwanted chemicals and compounds from your tank's water. The only external filtration component for Biofloc is used to remove larger waste particles from the system. The Biofloc system is less expensive than RAS because there is less technical equipment involved. Recent research and developments in indoor Litopenaeus vannamei farming indicates that combining technologies—specifically using Biofloc Technology (BFT) for nurseries followed by Recirculating Aquaculture Systems (RAS) for grow-out—yields superior performance. BFT excels in early stages with higher survival rates, while RAS offers better water quality management and higher final yields in grow-out, balancing growth, cost, and system robustness.
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  2 a. Recirculating AquacultureSystem b. Bio-floc technology c) View of RAS and Bio-floc under Culture Fig.1 Thematic view of RAS, Bio-floc with fish culture tanks Bio-floc formation Fig.2 methods of Bio-floc formation 3.1 The following finfish and shellfish species successfully cultivated using RAS, biofloc, or a hybrid of both systems worldwide: i) Finfishes (Freshwater): Pangasius/striped catfish, Murrel, Asian seabass, Rainbow Trout, GIFT Tilapia, Catfishes, Carps, other fin fishes and shell fishes ii) Finfishes (Marine & Brackish water): Barramundi / Asian Sea Bass, Groupers & Snappers, Salmonids, Other Species as Rachycentron canadum (Cobia), Trachinotus blochii (Silver pompano), and Mugil cephalus (Grey mullet) iii) Shellfish Species Cultivated in RAS and Biofloc: Pacific White Shrimp (Litopenaeus vannamei), Black Tiger Shrimp (Penaeus monodon), Giant Freshwater Prawn (Macrobrachium rosenbergii), other species as Fenneropenaeus indicus (Indian white prawn) Natural transition approach (maintain the ratio of C: N (12–15:1) Inoculum Approach Customization approach Addition of fertilizers, shrimp /fish feed Powdered bio-floc mass & Carbon source Use of lactic acid bacteria for bio-floc production External carbon source added Easy& fast process for bio-floc generation
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  3 and various mudcrab species like Scylla serrata are sometimes raised in biofloc-based nursing stages. Bivalves Species as Crassostrea gigas (Pacific oysters) and Mytilus edulis (Blue mussels) are grown in specialized marine RAS environments, mostly for seed production and sustainable shellfish farming 3.2 Ideal water quality parameters for successful RAS and bio-floc technology: 1) Dissolved oxygen (DO) >Above of 5.0 mg L−1 (ideal) and at least 60% of saturation. 2) Temperature 28-30° C 3) pH 6.8-8 4) Salinity: depends on cultured species 5) TAN &Nitrite <1 mg L−1 (ideal) 6) Nitrate 0.5–20 mg L−1 7) Orthophosphate: 0.5–20 mg L−1 8) Alkalinity More than 100 mg L−1 9) Settling solids (SS): Ideal: 5–15 mL L−1(shrimp), 5–20 (tilapia fingerlings) and 20–50 mL L−1(juveniles and adult tilapia) 10) Total suspended solids (TSS): <500 mg L−1 Table1. System Suitability Comparison Feature Recirculating Aquaculture Systems (RAS) Biofloc Technology (BFT) Primary Species Fit Carnivorous, herbivorous, and omnivorous finfish Omnivorous/detritivorous shrimp and tilapia Water Clarity Crystal clear (mechanical/biological filtration) Turbid (high suspended solids/microbial mass) Capital Investment Very High (requires specialized infrastructure) Moderate (requires heavy aeration and carbon input) Dietary Supplementation 100% reliant on formulated feeds Animals eat both feed and the live biofloc Table2. Realistic Production Expectations at existing fish species seed availability Parameter Bio-floc Technology (BFT) Recirculating Aquaculture System (RAS) Primary Suitability Shrimp (L. vannamei), Tilapia, Catfish and few other fin fishes and shell fish species Barramundi/Asian seabass, Shrimp, GIFT Tilapia, Pangasius, cold water trouts, Salmonids, few other finfishes and shell fish species Realistic Density 10 – 30 kg per m³ 40 – 80 kg per m³ Capital Investment Low to Moderate Extremely High Operational Costs Moderate (High carbohydrate/pumping cost) High (Continuous mechanical filtration/UV) Water Quality Risk High Nitrite/TSS spikes Rapid Ammonia spikes on filter failure 4. Challenges: Climate change, disasters, overpopulation, associated pollution, lack of adequate land and water resources, the risk of spreading diseases, lack of alternatives for the complete
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  4 replacement of antibiotics,antimicrobial resistance (AMR), and water quality-related environmental degradation are significant challenges. Additionally, high post-harvest losses, high input costs, lack of adequate support at the state level, and lengthy processes for licenses and electricity supply connections contribute to delays. Furthermore, many Biofloc and Recirculating Aquaculture System (RAS) units fail because producers lack the necessary support and technical expertise in daily microbial management. Accumulating sludge at the bottom of the tank turns anaerobic, releasing fatal doses of hydrogen sulfide and methane, which leads to unstable water quality, oxygen crashes, and disease outbreaks. High electrical dependence and mechanical breakdowns also frequently may cause catastrophic and sudden stock-economic losses 5. Advantages of RAS and Bio floc technologies: This technologies are well suited as proved worldwide commercial aquafarming, in land resources limited, water scare/dry areas and urban areas Way forward to overcome Challenges and Achieve Realistic Production in Bio-flocs and RAS units: 1. Implement Advanced Solids and Sludge Management Incorporate Clarifiers, Compartmentalised Design, Central Drainage, Precision Biology and Carbon Tracking, Automate C:N Ratios, Deploy Pure Heterotrophic Probiotics, Maintain Buffer Alkalinity 2. Optimize Infrastructure for High Density: a) Redundant Aeration & Automation b) Incorporate Multi-Phase Nurseries: Instead of stocking post-larvae directly into large grow-out units, leverage Biofloc as a highly nutritious, biosecure intermediate nursery phase. Move stronger, larger juveniles into RAS units later to optimize feed conversion ratios (FCR). c) Employ Smart IoT Monitoring: Utilize digital sensors to monitor dissolved oxygen (DO), temperature, and pH levels continuously. Catching a drop in DO early protects gill health and preserves historical growth curves. 3. Optimize Water Quality & Solid Management: a) Install Settling Cones/Clarifiers: Continually remove heavy suspended solids mechanically before they break down into toxic waste. b) Rigorous Aeration: Utilize bottom aeration (such as radial diffusers) to ensure constant turbulent mixing. This suspends the bio-floc, preventing the creation of dangerous anaerobic zones on the tank floor c) Real-time Monitoring: Adopt low-cost IoT sensors to monitor and control parameters like dissolved oxygen, pH, and ammonia to prevent environmental crashes. 4. Enhance Biological & Feed Management a) Strict C:N Ratio Control: Use measured, inexpensive carbon sources like molasses or tapioca flour alongside high-quality commercial feeds to foster healthy, nitrogen-consuming heterotrophic bacteria b) Probiotics: Introduce premium, targeted probiotics (e.g., Bacillus strains) to outcompete harmful bacteria and boost the innate immune response of your shrimp and fish.
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  5 5. Improve SystemDesign & Biosecurity a) Backup Power Systems: Invest in automatic power backups (such as diesel generators) and battery-powered aeration to prevent stock death during grid failures. b) Compartmentalize Operations: Do not stock a massive single-unit volume without a backup. Set up smaller, independent, compartmentalized tanks to prevent a disease outbreak in one section from wiping out the entire farm. 6. Strengthen Financial & Market Viability a) Target the Right Species: Focus on species that command a high market price per kilogram (e.g., Pacific Whiteleg Shrimp / L. vannamei, Tilapia, or Barramundi) to justify the intensive energy and operational costs. b) Leverage Government Support: Check with local agricultural and fisheries departments for capital subsidies or soft loans tailored to intensive aquaculture adoption. 6. Unit Costs under various schemes promoted RAS & bio-flocs units Table3. Statement showing particulars of schemes promoting RAS and bio-flocs, along with average revenues and production capacities, and the maximum possible revenue from various RAS and bio-flocs units. Particulars Component Large RAS Mediu m RAS Small RAS Large Bio-floc Medium Bio-floc Small Bio- floc Technical Configuration Specifications Minimum 8 tanks of 90 m³ each (Capacity: 40 tons/crop) Minimu m 6 tanks 1 tank of minimum 100 m³ capacity 50 tanks of 4 m diameter × 1.5 m height 25 tanks of 4 m diameter × 1 m height 7 tanks of 4 m diameter × 1.5 m height Maximum production of fish (Tilapia at ₹130–140/kg) 40MT/crop 10MT/c rop 4MT/crop 30.0 MT 15.0 MT 4.2 Metric Tons (MT) Maximum production of Shrimp(₹350– 400/kg) 18 to 20 Metric Tonnes 8 to 10 Metric Tonnes 2 to 3 Metric Tonnes 2,500 kg to 3,750 kg 930 kg to 1,250 kg 350 kg to 525 kg Average Estimated Net Profit (Rs. in Lakhs) ₹38.0 – ₹42.0 Lakh ₹16.0 – ₹22.0 Lakh ₹3.5 – ₹6.5 Lakh ₹11,25,00 0 – ₹16,87,50 0 per crop ₹4,18,500 – ₹5,62,500 per crop ₹1,57,500 – ₹2,36,250 per crop Supporting Scheme of DoF, GOI under various schemes PMMSY Unit Cost (Rs.) Rs.50.00 Lakhs 25.00 Lakhs 7.50 lakhs Rs.50.00 Lakhs 25.00 Lakhs 7.50 lakhs No of Units limited Subsidy on unit cost (General - 40%) 20.00 Lakhs 10.00 Lakhs 3.00 Lakhs 20.00 Lakhs 10.00 Lakhs 3.00 Lakhs Subsidy on unit cost 30.00 Lakhs 15.00 Lakhs 4.50 Lakhs 30.00 Lakhs 15.00 Lakhs 4.50 Lakhs
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  6 (SC/ST/Women - 60%) Entrepreneur Model (Under PMMSY) Followsthe standard PMMSY framework of 40% for general individuals/firms and 60% for women-led or SC/ST entrepreneurs, often capped at ₹1.5 crore on a maximum project cost of ₹5 crore FIDF Unit Cost - - - - - - No of Units Unlimited Subsidy Up to 3% interest subvention support on 80% of total project (total no of units cost) and 25% credit guarantee cover with maximum ceiling upto Rs.12.50 crore. With maximum repayment period of 12 years including 2 years of moratorium period Note: Production estimates are based on typical stocking densities (20-40 fish/m3 ) or 125-500 shrimp/PL per(m2 ). 7. Success stories on Biofloc Technology (BFT) Biofloc is ideal for small-scale and decentralized farming due to its lower setup costs and self-sustaining feed mechanism 7.1 Examples & Returns Smallholder Unit (Kerala, India): Investment: An initial fixed cost of approx. ₹40,000 to ₹100,000 per tank installation.Production: 1.2 tonnes (two crops per year) of Genetically Improved Farmed Tilapia (GIFT). Economic Returns: Generates a net annual profit of roughly ₹71,600, yielding a Return on Investment (ROI) of 16.5% to 71% depending on the scale and crop cycle 7.2 Commercial Scale (Goa, India): Scale/Production: Farmers operating multi-tank biofloc systems scaled up production from 2 tonnes to over 22 tonnes of Seabass, Tilapia, and Murrel. Economic Returns: High-density cultivation yields a net profit margin of ₹30,000 to ₹40,000 per tank every 6 months. 8. Success stories on Recirculating Aquaculture Systems (RAS) RAS systems require heavy upfront capital (CAPEX) but can generate massive volumes of fish in biosecure, land-based facilities 8.1 Micro Commercial Unit (Assam, India): Investment: A multi-tank setup in Northeast India typically costs around ₹15–20 lakh to build. Production: Yields 40 to 45 tonnes of fish per system. Economic Returns: Annual turnover reaches ₹14.8 to ₹20 lakh, providing an attractive regional cash crop return 8.2 Large Commercial Scale (USA & Europe): Investment: Large-scale commercial salmon operations (e.g., 2,500-tonne capacity) require capital expenditures up to ($60) million, with about (45%) going strictly to technological equipment. Production: Pioneers like Atlantic Sapphire target multi-thousand-tonne (e.g., 4,400+ tonnes) yields. Economic Returns: Optimal conditions yield an Internal Rate of Return (IRR) between (20%) and (30%), and a 3 to 10-year payback period.