Shrimp Growout Time

Shrimp Grow-Out Time vs Water Temperature

Marine shrimp like Litopenaeus vannamei react strongly to water temperature. Keep them at the optimum of 28–30°C and post-larvae stocked at PL10–PL12 will hit a commercial size of 12–18 g in 90–120 days. The rule the calculator uses is straightforward: every 1°C you fall below that thermal sweet spot tacks on roughly 3–5% to the total days. Drop below 22°C and feeding falls apart while mortality climbs fast.

Shrimp shed their exoskeleton every 7–10 days. Right after each moult they are soft and exposed, which is when cannibalism, predation and disease take their toll. Try to hold salinity in the 15–25 ‰ (ppt) band. Go lower and osmoregulation suffers, slowing growth; go higher and you just pay more for feed without a bigger harvest. In Rio Grande do Norte, Brazil's biggest producer, well-run semi-intensive ponds tend to report FCR somewhere between 1.2 and 1.6.

Applications

Carcinicultura farms lean on this to plan stocking, project biomass, schedule paddlewheels and pick harvest windows. It also helps when you weigh a tropical site that runs all year (Northeast Brazil, Ecuador) against a subtropical one (south Brazil, Mexico), where the winter slump can stretch a cycle by 20–40%.

FAQ

How many cycles per year are realistic? In the Brazilian Northeast, at 28–30°C, a pond usually turns out 2.5–3 cycles a year. Subtropical farms often get only 1.5–2.

What is the impact of WSSV (white-spot virus)? Outbreaks tend to track thermal stress. Run a cycle at 24°C or colder and the risk of mass mortality jumps considerably.

Can the formula be used for freshwater prawn? No. Macrobrachium rosenbergii grows on a different curve and has its own salinity requirements, so you'll want a model built for that species.