Shrimp biomass & FCR estimator from daily feed
From the feed you log each day and the size from your cast-net sample, the estimator works out the kg of shrimp in the pond, the count, survival and feed-inferred FCR. Pick the tab for your stage and fill in 2–3 cells to get results, with the assumptions shown. Use Samples & FCR to cross-check counted samples, measured weights and period accounting. Keep a pond log for charts, alerts and Excel export.
Shrimp in the nurseryAuto
Fill in total feed and sampled size in the yellow cells — results appear instantly.
Match the method to the culture stage
Use “Samples & FCR” for independent cross-checks. A sample estimates mean weight; it does not by itself reveal pond abundance. Result accuracy depends on representative samples, calibrated scales and complete records.
- Nursery: Record starting count and size; check drained batch weight and representative counted samples when transferring. Feed marks alone cannot establish survival.
- Transfer: Weigh container tare and retained water separately. Sum net batch weights; pool counts and weights instead of averaging shrimp/kg ratios.
- Grow-out: Sample representative locations and log the sampling date. Feed-based inference assumes a suitable ration rate; appetite changes can move the estimate without a population change.
- Finishing / partial harvest: Record each weighed harvest and live transfer. Include removed biomass in production; subtract additions. Do not treat sold shrimp as mortality.
- Whole crop: Sum feed for all stages and use external opening/closing stock and harvest. Internal transfers cancel; a simple average of stage FCRs is incorrect.
Production FCR for one period = feed supplied ÷ (closing biomass + harvest + live transfers out − opening biomass − additions). After complete harvest, closing biomass is zero and the harvested lot must appear only once.
Sources support the method, not a universal feeding/survival coefficient. The 3-day feeding average is only a conditional management aid, not a measured population count. These changes do not establish a percentage accuracy without independent farm validation.
Sources and calculation check
- FAO — Sampling and analysis
- FAO — On-farm feeding and feed management (2013)
- Nursery study — Revista Brasileira de Zootecnia (2018)
- Akiyama & Yukasano — Shrimp feed management (2024)
Arithmetic check of the outdoor-pond article example: 65 / 0.027 = 2,407.4 kg; at 14 g/shrimp this is about 171,958 shrimp, or 86.0% of 200,000 stocked. The printed 146,214 shrimp / 73.1% does not match those inputs.
What is the estimator based on?
- Grow-out: biomass = whole-day feed ÷ feed rate for the size; count = biomass × size (shrimp/kg). E.g. 50 kg ÷ 5.5% = 909.1 kg of shrimp × 100/kg ≈ 91,000 shrimp.
- Nursery: count = total feed since stocking ÷ feed mark per 100,000 shrimp × 100,000 (marks: 220 kg at 500/kg, 250 kg at 400/kg — reference marks, adjust them to your own pond).
- Transfer: subtract container tare and measured retained water. Quick-calculation container factors are assumptions requiring calibration. Use Samples & FCR for measured inputs; estimate lot count from net lot weight and representative sampled size.
- Survival = estimated count ÷ number stocked. Feed-inferred FCR = cumulative feed since stocking ÷ (estimated biomass − stocked weight); stocked weight = number stocked ÷ stocking size.
- No-feeding days (0 kg of feed — moulting, water treatment): biomass is not estimated that day, but the feed still counts towards the cumulative total.
| Shrimp size (/kg) | Feed rate (Southern Vietnam practice) | kg feed / 100 kg shrimp |
|---|---|---|
| 500 | 10% | 10 |
| 400 | 9% | 9 |
| 300 | 8.5% | 8.5 |
| 200 | 7.75% | 7.75 |
| 150 | 6.5% | 6.5 |
| 100 | 5.5% | 5.5 |
| 40 | 3.35% | 3.35 |
| 30 | 2.65% | 2.65 |
| 20 | 2.1% | 2.1 |
This empirical table has not been validated against independent pond data. Ration rates vary with stock, size, feed, temperature, oxygen and culture system. Feed-inferred biomass cannot independently validate FCR. Calibrate with counted samples and actual weighed harvests; do not increase feed to improve a displayed estimate.
When does the estimator warn you?
- Estimated survival above 100%: the feed table may be too low for this pond, or the size entered may be off — re-sample to check.
- Count drops more than 10% over 3 consecutive days with no change in size: feeding has declined; this does not establish mortality. Check ration changes, trays, oxygen and re-sample.
- Feed-inferred FCR rises more than 0.15 within 7 days: check records against independent biomass measurements; ration reduction alone can raise this inferred index.
- More than 7 days without a sample: the old size makes results less accurate over time.
The pond log is stored on your phone only and never sent to a server. Technical support: +84 867 957 568.
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