The tambaqui (Colossoma macropomum) is a freshwater species of serrasalmid. It is also known by the name black pacu. The tambaqui is the largest characin of South America. The tambaqui is found in the Amazon and Orinoco basins in its wild form. It may reach more than 1 m (3 ft 3 in) in total length and 30 kg (66 lb) in total weight. It is similar in shape to the piranha and is sometimes confused with the carnivorous fish; the tambaqui is tall and laterally compressed with large eyes and a slightly arched back. Body color is basic black to gray with spots and blemishes in its mid body. All the fins are black and the pectoral fins are small.