Biofloc fish farm guide
Biofloc Fish Farm Planning: Tank Sizing, Feed Rates and FCR
How do you plan a biofloc fish farm?
Size it from the tonnage you want to sell. Divide each cycle's harvest by a stocking density your aeration can support to get culture volume, set daily feed as a percentage of the fish's body weight, and multiply annual output by a conservative FCR to get the feed you must buy. Those three numbers drive tanks, blowers, backup power and feed budget.
Quick sizing, feed and FCR calculator
Indicative planning figures only — not engineering design.
- Peak biomass per cycle
- 50,000 kg
- Culture volume needed
- 2,000 m³
- Tanks of 94.2 m³
- 22
- Peak daily feed
- 1,000 kg/day
- Annual feed
- 160 t/yr
Assumes all units hold harvest-density biomass at once (worst case for aeration and feed) and circular tanks.
How do I size biofloc tanks or lined ponds?
Culture volume = harvest biomass per cycle ÷ stocking density at harvest. Example: 100 t/yr in 2 cycles is 50,000 kg per cycle; at 25 kg/m³ that needs about 2,000 m³ — roughly 22 circular tanks of 10 m diameter and 1.2 m water depth.
- Start from the tonnage you can sell, not from the tanks you can afford.
- Pick a stocking density your aeration, backup power and team can sustain; higher density raises oxygen demand and solids load.
- Add nursery volume and at least one spare unit for transfers, cleaning and emergencies.
- For lined ponds, measure actual water volume with the pond volume calculator rather than nominal area.
- Keep unit size within what one person can harvest and drain in a working day.
How much should biofloc fish be fed per day?
Daily feed = standing biomass × feed rate (% of body weight). The rate falls as fish grow; the table below summarises published Nile tilapia biofloc feeding-rate trials. They are small-tank research results for one species, so your feed supplier's table, water temperature and observed appetite still decide the daily ration.
| Fish size | Result in biofloc trials (% body weight/day) | Source |
|---|---|---|
| Nursery, 3–30 g (trial start 3.1 g, 70 days) | 6.1% best growth; 4.3% best economic return | Oliveira et al. 2021 |
| Juvenile, from 12 g (4 weeks) | 6% best growth; 4% and 8% not significantly different; FCR worsened as feed rose | Villes et al. 2024 |
| Mid grow-out (about 30–150 g) | No biofloc trial found — use your feed supplier's table | — |
| Fattening stage | 1.4% performed best vs a 2.0% control | Elnady et al. 2023 |
- Feed small meals often for fingerlings; reduce frequency as fish grow.
- Cut feed when dissolved oxygen is low, temperature drops or fish stop feeding.
- Uneaten feed is doubly costly in biofloc: it raises ammonia and floc load and therefore aeration demand.
- Log feed per tank daily; it is the basis for FCR and for carbon dosing.
What is FCR and why does it decide biofloc profit?
Feed conversion ratio (FCR) is kilograms of feed used per kilogram of fish produced. Feed is usually the largest operating cost, so a farm at FCR 1.8 buys about 12% more feed than one at 1.6 for the same harvest.
- Plan with a conservative FCR for your species, feed and site; treat better figures as upside.
- Biofloc can improve conversion because fish graze on the floc, but this is not guaranteed.
- Annual feed (t) = annual production (t) × FCR — budget storage and cash for it.
- Ask every supplier which FCR their design and business case assume.
Planning checklist before requesting quotes
- Annual tonnage, species, harvest weight and cycles per year written down
- Stocking density chosen and justified by aeration and team experience
- Culture volume and number and size of tanks or lined ponds
- Peak daily feed and annual feed tonnage at a conservative FCR
- Aeration and backup power sized for peak biomass, with automatic changeover
- Solids removal and a permitted sludge discharge route
Sources
- Oliveira L.K. et al. (2021). Growth, nutritional efficiency, and profitability of juvenile GIFT Nile tilapia reared in biofloc on graded feeding rates. Aquaculture 541: 736830
- Villes V.S. et al. (2024). Feeding rates affect growth, metabolism and oxidative status of Nile tilapia rearing in a biofloc system. Tropical Animal Health and Production
- Elnady M.A. et al. (2023). Growth and feed performances of the Nile tilapia during the fattening stage under restricted feeding in biofloc culture. Egyptian Journal of Aquatic Biology & Fisheries 27(3): 69–85
FAQ
- How big should biofloc tanks or ponds be?
- Work backwards from production. Divide the peak standing biomass you need by a realistic stocking density (often 15–40 kg/m³ for tilapia in biofloc, set by your aeration and operator skill) to get the culture volume, then split it into units you can manage and harvest. The calculator on this page does the arithmetic.
- How much feed does a biofloc fish farm use per day?
- Daily feed is the standing biomass multiplied by a feed rate expressed as a percentage of body weight. In Nile tilapia biofloc trials, 3–30 g fish grew best at about 6% of body weight a day (4.3% was most profitable), while fattening-stage fish did best at 1.4% against a 2.0% control, so feed demand falls through the cycle. Use the supplier feeding table for your feed and temperature.
- What FCR should I plan for in biofloc?
- Feed conversion ratio is kilograms of feed per kilogram of fish produced. Plan with a conservative figure from your species, feed and site — not a supplier's best-case claim — and test how a higher FCR changes feed cost before committing. Biofloc may improve conversion because fish graze on the floc, but this is not guaranteed.
Tools and related guides
Ready to get comparable quotes?
Send one project request for biofloc projects from about USD 250,000. Our team reviews it, contacts suitable suppliers for you and presents comparable responses through FishMatch.
Start a project requestPlanning guidance only, not engineering design or financial advice. Densities and FCR are typical starting points and feed rates come from small research trials, not guarantees; confirm them with your feed supplier and a qualified engineer.