Essential Pond Water Parameters for Healthy Shrimp

Dissolved oxygen supports shrimp respiration, feed utilisation and the beneficial biological processes that transform organic waste and nitrogen compounds.

Oxygen normally changes throughout the day. Photosynthesis can increase oxygen during daylight, while shrimp, plankton and microorganisms continue consuming oxygen at night. For this reason, the lowest concentration is often observed close to sunrise.

A commonly used management objective is to keep dissolved oxygen near or above 5 mg/L, but the correct response should consider biomass, temperature, feeding rate, weather and pond conditions.

pH influences shrimp physiology, pond productivity and the toxicity of compounds such as ammonia. FAO shrimp guidance commonly describes approximately pH 7.5 to 9.0 as suitable, while narrower farm targets may be used according to the culture system.

A single pH result is less informative than the daily pattern. Morning pH is generally lower after overnight respiration, while afternoon pH may rise as photosynthesis removes carbon dioxide.

Large daily swings may indicate excessive plankton activity, limited buffering or unstable pond conditions. Management should focus on the cause of instability rather than reacting to one isolated reading.

Temperature influences shrimp metabolism, appetite, oxygen demand, growth and the chemical balance between ammonium and un-ionized ammonia.

Published shrimp-farm guidance often cites approximately 28 to 33°C as a useful reference range, but the appropriate target depends on species, life stage, acclimation and local production conditions.

Warm water holds less dissolved oxygen while biological oxygen demand may increase. Sudden cooling after heavy rain can also change pond mixing and shrimp behaviour.

Vannamei shrimp can be cultured across a broad salinity range when properly acclimated, but rapid salinity change can create osmotic stress even when the final value would normally be tolerated.

Some traditional shrimp-farm guidance lists approximately 15 to 35 ppt as a reference range. Modern Vannamei farms may operate outside this range, so a universal target should not be applied without considering local water chemistry and acclimation.

Rainfall, evaporation, source-water changes and water exchange can shift pond salinity. The rate of change is often as important as the measured value.

Total alkalinity represents the water's capacity to neutralise acids and resist sudden pH change. It supports pH stability and biological processes involved in pond productivity and nitrification.

Hardness describes dissolved calcium and magnesium and is not the same as alkalinity. Both can matter in low-salinity culture, mineral balance and shrimp moulting management.

Required levels vary by production system and source-water chemistry. Results should be reviewed as trends and interpreted alongside pH, salinity and mineral composition before corrective products are selected.

Feed, shrimp waste, dead plankton and organic sludge contribute nitrogen to the pond. Microorganisms transform these materials through a cycle that includes ammonia, nitrite and nitrate.

The toxicity of ammonia depends strongly on pH and temperature because these conditions influence the proportion present as un-ionized NH₃. A TAN result should never be interpreted by itself.

Nitrite can interfere with oxygen transport and may become more concerning under low-chloride conditions. The correct response depends on concentration, salinity, chloride, oxygen, feeding and pond biology.

Transparency provides a practical indication of suspended particles and plankton density. Traditional shrimp guidance commonly references Secchi-disc visibility around 25 to 45 cm, but interpretation depends on pond depth, soil particles, plankton type and culture intensity.

Very dense plankton can produce high afternoon oxygen and pH but also consume substantial oxygen overnight. Sudden colour loss may indicate a plankton crash and increased organic decomposition.

Pond colour should be assessed together with Secchi depth, dissolved oxygen, pH trend and microscopic or laboratory observations when available.

Useful monitoring is consistent, comparable and connected to management decisions. Measure at the same locations, depths and times whenever possible, and record weather, feeding, aeration and shrimp behaviour alongside numerical results.

Parameters that can change quickly, such as dissolved oxygen, temperature and pH, generally require more frequent checking than slower-changing parameters. Monitoring frequency should increase during high biomass, unstable weather, plankton changes or disease-risk periods.

Meters and test kits should be maintained, calibrated and used according to the manufacturer's instructions. A questionable result should be checked before a major corrective action is taken.