01 · AquaGrow
What it is
Salinity is the salt content of water, usually measured in parts per thousand (ppt). Shrimp need time to adjust to a change. An abrupt change can cause stress; the response depends on life stage and water chemistry.
Signs to watch for
- A sharp salinity change from the pond’s recent readings.
- Poor feeding or unusual swimming after rain or pumping.
- Different readings near the surface and lower in the pond.
Common causes
- Heavy rain adds a fresh-water surface layer.
- Source water differs greatly from the pond.
- Water is added or exchanged without checking salinity first.
How to confirm the cause
- Use a checked refractometer or salinity meter. Compare representative surface and lower-water readings safely.
- Test the proposed source water and record temperature, pH and DO with the salinity trend.
What to do immediately
- 1
Check salinity at representative points and depths and record how quickly it changed.
- 2
Maintain safe aeration and monitor DO. Pause feed if shrimp are distressed.
- 3
Stop unplanned water additions. Do not dump salt or mineral mixtures into the pond as a quick fix.
- 4
Ask a technician for a gradual, tested water-management plan. Do not suddenly reverse the change or flush untreated water out.
Prevention: your practical checklist
- Check source and pond water before every exchange.
- Maintain rain and overflow plans that protect biosecurity and avoid abrupt changes.
- Use a stage-specific acclimation plan for seed; the grow-out reference is not a hatchery transport rule.
When to call an expert
- Call urgently if a rapid salinity change is followed by distress or deaths.
- Get help before changing water if large vertical differences or repeated rain-related problems are found.
Farmer questions
What does ppt mean?
Ppt means parts per thousand. It is the usual unit for salinity. It is not the same as ppm, which is used for many water-quality concentrations.
Should I quickly return to the old salinity?
No. Another sudden change can add stress. Test the water and ask for a gradual plan suited to the shrimp stage and pond.
Can one surface reading describe the whole pond?
Not always, especially after heavy rain. Compare representative depths safely and discuss any layering with a technician.
Sources & further reading
AI-assisted educational content and translations, source-checked 17 October 2026. Not an individual diagnosis or prescription. Independent aquaculture-health and native-language specialist approvals have not been supplied. Sources do not endorse AquaGrow.