Brackishwater is water having a somewhat salty taste. A more quantitative definition of brackishwater is water with salinity between 0.5 and 17 parts per thousand.
Some species of Macrobrachium prefer clearwater rivers while other, including Macrobrachium rosenbergii are often found in extremely turbid conditions.
Macrobrachium rosenbergii grows to maturity in freshwater. There are four distinct phases in the life cycle of the fresh water prawn namely eggs larvae, postlarvare (PL) and adults.
From hatching to metamorphosis into juveniles the actively swimming large undergo 11 moults and metamorphose into post-larvae with 3-7 weeks, depending on temperature, water quality and food supply.
Post-larvae become benthic and migrate upstream from saline conditions to compete their life cycle in freshwater.
If cultured under good pond conditions and with an ample supply of rich food, young prawns of about 4 to 5 cm in length and 1 to 2 g in weight are able to grow to about 20 cm, weighing about 100 g, in 5 to 6 months.
Macrobrachium rosenbergii life cycle