Pacu, << PA kyoo, >> is the common name for several species of South American freshwater fish. Pacus have a narrow, plate-shaped body. Some pacus look much like piranhas, to which they are closely related. However, unlike piranhas, pacus have blunt teeth and eat plants and plankton (small, drifting water organisms). Piranhas have sharp teeth and eat fish. Some small pacus are popular for home aquariums.
The black pacu may grow to more than 3 feet (90 centimeters) long and weigh over 65 pounds (30 kilograms). It is found in rivers throughout the Amazon region. In Brazil, where it is called tambaqui, the black pacu is an important commercial food fish. During the long rainy season, adult black pacus migrate far from the main branches of the Amazon River into flooded parts of the tropical forest. There they eat fruits that fall into the water, spreading the seeds. When the floodwaters go down, black pacus return to the main river channels. They stay there, eating little, until the next rainy season.
