How Shrimp Farm calculates metrics
Last updated: July 18, 2026 · English master
Shrimp Farm calculates metrics locally from records you enter. The same inputs produce the same outputs offline. These calculations support record review; they are not veterinary, chemical, treatment or real-time safety advice.
Core formulas
Canonical units are grams (g), kilograms (kg), square metres (m²), degrees Celsius (°C), parts per thousand (ppt) and milligrams per litre (mg/L). Daily boundaries and DOC use the farm's confirmed local timezone. If required inputs are missing or a denominator is invalid, the app shows the metric as unavailable rather than inventing a value.
| Metric | Calculation | Important limitation |
|---|---|---|
| DOC | Farm-local date today − stocking date | Depends on the confirmed farm timezone. |
| Average body weight (ABW) | Sample total weight (g) ÷ sample count | Represents the recorded sample, not every shrimp in the pond. |
| Estimated shrimp count | Stocked count − observed mortality − harvested count | Mortality is observed and normally a lower bound. |
| Estimated survival | (Stocked count − observed mortality) ÷ stocked count × 100% | Usually overestimates true survival when mortality is under-observed. |
| Estimated standing biomass | Estimated shrimp count × latest ABW (g) ÷ 1,000 | Inherits uncertainty from mortality and sampling. |
| Produced biomass | Standing biomass + harvested biomass − initial biomass | Must be greater than zero before FCR is shown. |
| Feed conversion ratio (FCR) | Total feed (kg) ÷ produced biomass (kg) | Estimated until the cycle data are complete; not calculated for an invalid denominator. |
| Average daily gain (ADG) | (Current ABW − previous ABW) ÷ elapsed days | Requires two valid samples on different dates. |
| Feeding rate | Recent daily feed (kg) ÷ estimated standing biomass (kg) × 100% | Only as reliable as the biomass estimate and selected feed window. |
| Harvest ETA | (Target ABW − current ABW) ÷ positive ADG | A low-confidence linear projection, not a promise; unavailable when growth is not positive. |
How confidence is communicated
- Observed describes what was directly logged, such as recorded mortality.
- Estimated marks values that depend on sampling or incomplete mortality counts.
- Missing or stale inputs are shown explicitly; the interface does not imply false precision.
- Alerts explain the triggering record and threshold. They do not prescribe a treatment or dose.
Sources and provenance
The arithmetic above is Shrimp Farm's documented product contract. External publications inform domain terminology, data-quality caveats and the evidence register used when thresholds or knowledge cards are reviewed. They do not imply that FAO, SEAFDEC, CAA, EPA, NACA or any author endorses Shrimp Farm, and no single source validates every formula or threshold.
- FAO — Cultured Aquatic Species Information Programme: Penaeus vannamei
- FAO — Pond culture management manual
- SEAFDEC/AQD institutional repository
- SEAFDEC/AQD — growth and survival research record (Chen, 1985)
- Lin & Chen (2001) — peer-reviewed salinity and ammonia study
- Lin & Chen (2003) — peer-reviewed nitrite study
- Coastal Aquaculture Authority of India — shrimp-farm guidelines
- US EPA — dissolved oxygen criteria background
- Network of Aquaculture Centres in Asia-Pacific (NACA)
Evidence quality and applicability vary by species, life stage, system and location. Safety-adjacent thresholds require separate expert review before release; the app must never turn a general source into farm-specific treatment advice.
Questions or corrections
If a formula, limitation or source appears unclear, email contact@shrimpfarm.app. Corrections should update the written contract, deterministic engine and tests together.