Macrobrachium

Macrobrachium is a genus of freshwater prawns or shrimps characterised by the extreme enlargement of the second pair of pereiopods, at least in the male. The genus is cosmopolitan, found throughout the tropical, freshwater and estuarine ecosystems of both the Old and New Worlds. The genus has a difficult taxonomic history due to morphological conservation between its species (plesiomorphy), and conversely, variations within a single species (polymorphism), leading to the discovery of cryptic species which were only revealed through genetic analysis and morphometry.

Many species of Macrobrachium are of high commercial value, especially the larger species such as those from the M. rosenbergii species group; these are both shrimped and cultivated throughout the world. Escapees of aquaculture operations have been found to have established breeding populations, though their ecological impact is little studied.