Macrobrachium carcinus is a species of fresh water shrimp known as the big claw river shrimp. It is native to streams, rivers and creeks from Florida to southern Brazil. It is the largest known species of Neotropical freshwater prawn, growing up to long and weighing as much as , although even larger specimens have been reported. It is an important species for commercial fishing in the Sao Francisco area, where it is known by the local name of pitu. M. carcinus is omnivorous, with a diet consisting of molluscs, small fish, algae, leaf litter and insects. Macrobrachium carcinus has a tan or yellow body with dark brown stripes. Its chelae are unusually long and thin, to facilitate foraging for food in small crevices, and may be blue or green in colour. References Palaemonidae Crustaceans described in 1758 Taxa named by Carl Linnaeus Freshwater crustaceans of South America