Frequently Asked Questions: Expert Guidance

To maintain a 15:1 Carbon-to-Nitrogen ratio, add organic carbon (like molasses or sugar) based on the crude protein percentage and weight of the daily feed. For example, for 1 kg of 32% protein feed, roughly 100-150g of pre-dissolved molasses is required. You can use our interactive Biofloc Carbon Calculator on this site to get exact dosage amounts.

For tilapia and catfish, the target floc volume is 25 ml to 35 ml per litre of tank water measured after 30 minutes of settling in an Imhoff cone. If floc volume exceeds 40 ml/L, run sludge drain valves or reduce carbon dosing; if below 15 ml/L, boost probiotic and carbon supplementation.

Biofloc bacteria and dense fish populations both consume large amounts of oxygen. If aeration stops for even 30–60 minutes, Dissolved Oxygen (DO) plummets, causing floc to die and collapse into toxic sludge, resulting in immediate fish mortality. Always maintain backup power or air ring blowers.

A complete commercial RAS includes: 1) Swirl Separator/Drum Filter for solid waste removal, 2) Moving Bed Biofilm Reactor (MBBR) for nitrifying bacteria (converting Ammonia → Nitrite → Nitrate), 3) Protein Skimmer/Degasser for CO2 stripping, and 4) UV Sterilizer/Ozone for pathogen disinfections before re-entering culture tanks.

The MBBR biofilter holds plastic media (K1/K3/MBBR media) colonized by two strains of nitrifying bacteria: Nitrosomonas (converts toxic Total Ammonia Nitrogen into toxic Nitrite) and Nitrospira/Nitrobacter (converts Nitrite into relatively harmless Nitrate). Constant air fluidization keeps media suspended.

In commercial fish culture setups, the entire water volume of culture tanks should pass through the filtration loop at least 1.0 to 1.5 times per hour. High stocking density (60-100 kg/m³) requires even faster circulation rates to prevent ammonia accumulation.

Fish excrete ammonia through their gills and feces. Nitrifying bacteria in grow beds convert ammonia into nitrates, which serve as primary organic liquid fertilizer for plants (lettuce, spinach, tomatoes, herbs). The plants clean the water by absorbing nitrates before returning safe water back to the fish.

For leafy greens (lettuce, spinach, basil), target a pH range of 5.8 to 6.5 and an EC level of 1.2 to 2.0 mS/cm. In coupled aquaponics, a pH around 6.8 is the ideal compromise between fish safety (6.5-8.0), bacteria efficiency (7.5-8.0), and plant nutrient availability (5.5-6.5).

For traditional Indian Major Carp (Rohu, Catla, Mrigal) polyculture, stock 4,000 to 5,000 fingerlings per acre (10,000 to 12,500 per hectare). For intensive feeding ponds with paddlewheel aerators, density can be increased up to 10,000-15,000 fingerlings per acre.

During daytime, pond algae produce oxygen via photosynthesis. At night, algae and fish both consume oxygen, causing DO levels to crash to critical lows (below 3 mg/L) around 3:00 AM – 6:00 AM. Operating paddlewheel aerators overnight circulates surface water and maintains vital oxygen balance.

Polyculture maximizes natural pond feed across all water layers: Catla feeds on surface plankton, Rohu feeds on mid-water vegetation, and Mrigal/Cyprinus feeds on bottom detritus. This prevents feed waste and yields higher total tonnage per acre.

White Spot (Ichthyophthirius multifiliis) presents as tiny white sugar-like dots on fish skin and fins, accompanied by 'flashing' (fish scraping against tank walls). Isolate affected tanks, raise water temperature slightly (if species permits), and perform a 2-3% salt bath (20-30g salt per litre of water for 10-15 minutes) or treat with formalin/malachite green under expert guidance.

Ideal parameters for most tropical species (Tilapia, Carps, Catfish): • Dissolved Oxygen (DO): > 5.0 mg/L • pH: 6.8 – 8.2 • Total Ammonia Nitrogen (TAN): < 0.5 mg/L • Un-ionized Ammonia (NH3): < 0.05 mg/L • Nitrite (NO2): < 0.2 mg/L • Water Temperature: 26°C – 32°C

Potassium Permanganate is an effective broad-spectrum disinfectant for external bacterial gill rot, body fungus, and protozoan parasites. Apply a short dip at 2 to 4 mg/L in a clean quarantine tank. Avoid over-dosing as high concentrations can damage delicate fish gill filaments.

FCR measures how many kilograms of feed are required to grow 1 kilogram of fish body weight (FCR = Total Feed Given ÷ Total Weight Gained). An FCR of 1.2 to 1.4 is excellent in commercial aquaculture. Lower FCR means less feed waste and higher profitability.

Protein requirements decrease as fish mature: • Fry / Nursery (0.5g – 10g): 40% – 45% protein micro-pellets • Fingerlings (10g – 100g): 32% – 36% floating pellets • Grow-out (100g to harvest): 28% – 32% floating pellets

Yes! Modern Fisheries provides certified disease-free high-growth fish seed (Mono-sex Tilapia, Jayanti Rohu, Catla, Pangasius, Magur, and Shrimp post-larvae) with doorstep delivery support and oxygen-packing protocols across major farming regions.

Absolutely. We offer complete turn-key engineering solutions including site survey, tarpaulin tank setup, aeration system design, MBBR biofilter sizing, probiotic starter kits, and hands-on staff training. Contact our help desk (+919748952342) to request consultation.