Amazon river prawn

Macrobrachium amazonicum can grow to a length of 16 cm (6.3 in) and weight 30 g, with males on average larger than females. Males occur in four distinct morphotypes. The smallest morphotype, known as translucent claw (TC) is mostly translucent, with a greenish tinge. In the second smallest, cinnamon claw (CC), the green tinge is more marked but there are several brownish spots on the claws that make them look beige. In the two largest morphotypes, named green claw 1 (GC1) and green claw 2 (GC2), the second pair of chelipedes is very large and has a moss green color. In GC2, the chelipedes are longer than the body. Similar morphotypes also occur in the giant river prawn, Macrobrachium rosenbergii.

Macrobrachium amazonicum is found in Guayana, Surinam, French Guiana, Brazil, Colombia, Venezuela, Peru, Ecuador, Bolivia, Paraguay and Argentina. It occurs in all the main eastern South American river basins, such as the Orinoco, Amazon, Araguaia-Tocantins, São Francisco, and La Plata. In the São Francisco river Basin it is likely an introduced species, but has become widespread in the past decades.