Salinity requirements vary among species, but some of the commonly cultured species can survive exposure to 5 to 10 ppt or even lower. Salinities above 45 to 60 ppt can be lethal. Growth occurs between 15 and 30 ppt (Boyd & Fast, 1992).

Shrimp farms usually take their water from estuaries which are subject to seasonal influences. Salinity declines during the rainy season and increases in the dry season. In some places, salinity may vary from 5 to 10 ppt or less at the end of the rainy season to 30 to 40 ppt or more at the end of the dry season. Salinity changes are normally gradual, so it is not necessary to measure salinity more than once or twice weekly unless the water source is strongly influenced by tidal flows. Also, most ponds on a given farm will have almost identical salinities, and it is therefore unnecessary to measure salinity in each pond. The exception to this rule is where farms have multiple water sources of different salinities, such as in Taiwan. Salinity can be estimated from the chloride concentration:

Salinity also can be measured directly with hydrometers, hand-held salinometers (refractometers), or electronic salinometers (conductivity meters). Hand-held salinometers are recommended for practical use on shrimp farms. Conductivity meters are more useful in research applications (Boyd & Fast, 1992).