Shrimp feed calculator by days of culture — hand feeding & feeders

When to switch to a feeder?

• Usually from DOC 15–25, when shrimp are about 1.5–3 g and already eat pellets. Before that the feed is fine and amounts are small — broadcast by hand around the pond. The calculator assumes a switch at DOC 20.
• Switch over a few days: let the feeder spread part of the ration and keep hand-feeding the rest; watch trays near and far from the feeder, and hand everything to the feeder once shrimp feed evenly.
• Placement: 8–12 m from the dyke, 50–70 cm above the water. Put 2 check trays — one 1–2 m from the feeder, one 6–8 m away — and check them about every 2 hours in the first days (Tepbac). Add aeration around the feeding zone, since shrimp crowd there.
• Many small meals: in a 13-week Auburn University trial, shrimp on timer feeders (6 meals/day, 15–30% above the feed table) reached 25.1–27.5 g versus 19.7 g with hand feeding twice a day; an acoustic feeder reached 32.0 g. FCR and survival did not differ (Davis et al., 2018).
• Heavy rain: stop the feeder during rain or for the whole day (choose under Weather). Poor water — low DO, high toxic gases — cut feed by 50% or stop for 2–4 days (Akiyama & Yukasano, 2025).
• Medicated or supplemented feed: mix per hopper batch and let it dry before loading — wet feed jams the feeder.
• Tray checks with a feeder (Than Vuong summary table): set PAUSE 5 min — THROW 10 s. Tray empty before 4 min → shorten the pause (feed more often); not empty → lengthen to 6 min; then recalculate the day's feed.
• New feed size or worn spinner: re-measure the feed rate and reset the feeder.

How to change feed size?

• Go by sampled shrimp size, not by date: switch when most shrimp in your cast-net sample have reached the next size. The table is a guide — every brand numbers its feeds differently, so check the bag.
• Mix both sizes 50:50 for 2–3 days, then switch fully (Akiyama & Yukasano, 2025). In ponds with uneven sizes, mix for longer so small shrimp can still eat.
• Don't switch during a mass molt, right after heavy rain or when shrimp are weak — wait 1–2 days for things to settle.
• A new size often means new protein: the table is made for 40–42% protein feed. Feed less of a higher-protein feed and more of a lower-protein one, so shrimp get the same protein each day — e.g. 45% protein ×0.91, 35% ×1.17. Enter the protein in step 3 and the calculator adjusts.
• Feeders: larger pellets throw differently — re-measure the feed rate after switching.

Reading feed trays

The table is only a starting point — trays tell you how much shrimp actually eat. A 0.5 ha pond needs at least 4 trays, 1 ha 6–8 trays; day-to-day swings of 5–20% are normal (Akiyama & Yukasano, 2025).

Adjusting for water temperature

Measured pond temperature is what counts. Enter it in step 3 and the calculator applies the factor.

What is it based on?

• First month (DOC 1–30, no sample yet): feed by table, by number stocked — not by biomass. Whiteleg: day 1 = 0.7 kg per 100,000 (Than Vuong practice), rising evenly to match Than Vuong's summary table on day 30 — 2.5 g × survival × 10–11% (100,000 at 80% survival ≈ 20–22 kg a day) — so day 31 (by % of biomass) does not jump. For reference, the Thuy san Viet Nam magazine table starts at 2 kg and adds 0.2–0.5 kg a day (≈ 164 kg per 100,000 over 30 days). Black tiger: days 1–3 = 1.2–1.5 kg, then add 0.2 / 0.25 / 0.3 kg a day (Thuy san Viet Nam magazine). Farms with their own table can change the day-1 amount in the calculator. A trial in Indonesia with PL12 grew best at about 173 kg per 100,000 over 30 days (Fahrur et al., 2023). Shrimp below about 3.5–4 g are best fed by such a table (Akiyama & Yukasano).
• Biomass (from DOC 31 or with a sampled size, kg) = number stocked × survival × average weight (g) ÷ 1,000.
• Daily feed = biomass × feed % for the size (rainy → dry season) × temperature factor × protein factor.
• Feed % by size: Than Vuong summary table for 40–42% protein feed — from 10–11%/day at 2.5 g down to 2–2.3% at 50 g, interpolated between points.
• Protein factor (from day 31) = 41 ÷ feed protein, so shrimp get the same protein each day: 30% ×1.37 · 35% ×1.17 · 38% ×1.08 · 42% ×0.98 · 45% ×0.91. Trials feeding by this ratio gave the same growth (Davis & Venero 2005; Patnaik & Samocha 2009; Araujo et al. 2025), but FCR rises as protein falls: 1.08 at 40% → 1.20 at 35% → 1.37 at 30%. The calculator only works within 30–45%: below 30% extra feed is wasted without extra growth, above 45% further cuts leave shrimp short of energy. No protein adjustment in the first month.
• Size from DOC (whiteleg): milestones of Than Vuong's summary table — DOC 30 = 2.5 g, 40 = 5 g, 50 = 10 g, 60 = 14.3 g, 70 = 20 g, 80 = 25 g, 90 = 28.6 g, 100 = 30.3 g, 115 = 40 g, 125–130 = 50 g; black tiger follows the Nuôi Lời growth curve. Sample every 7–10 days and enter the real size for accuracy.
• Meals: afternoon/evening meals are larger, e.g. 4 meals 20–20–25–35%. Feeders: the daily total is split evenly across hopper refills within feeder hours. Timer feeders: throws = kg per batch ÷ g per throw; pause = run minutes ÷ throws, ideally 5–20 minutes.

A starting point only — always control with feed trays and the feed bag's table. Cut 30–50% after heavy rain or environmental shock; skip meals when DO is low or shrimp surface.

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