M. rosenbergii is nocturnal, bottom dwelling and sluggish in nature and is territorial. During the day they remain half buried in sediments and prefer shallow, detritus rich and vegetated areas.
The spawning season of M. rosenbergii is protracted and varies in different regions in its distributional range in the Indo-west pacific region. In temperate regions, the breeding season coincides with the summer, while in tropical regions it is generally restricted to the onset of the rainy season (Valenti, 1984). Spawning occurs two or more times per season (Ling and Merican, 1961).
Successful mating occurs between soft shelled females and hard shelled males. The mating process is described in detail by Ismael and New (2000) and Karplus et al. (2000). Gravid females migrate downstream into estuaries, where the eggs hatch as free swimming larvae. The larvae pass through 11 zoeal stages before reaching the post larval stage (Uno and Kwon, 1969).
Fecundity of M. rosenbergii varies considerably with the age, size and stage of maturity. According to New and Singholka (1982), the giant river prawn lays between 0.8 to 1.0 x104 eggs during one spawning. The eggs of M. rosenbergii are slightly elliptical with a long axis of 0.6-0.7 mm, and are bright orange in colour until 2 or 3 days before hatching, when they become grey-black (Ling, 1969; Manus et al., 2006).
The zoea are planktonic, swimming upside down within the water column and exhibit positive phototaxy. Larval development is temperature dependent. After metamorphosis, the PL assume a benthic lifestyle and begin to migrate upstream into freshwater. Post larvae resemble miniature adult prawns and swim with the dorsal side uppermost (New and Singholka, 1985).