Pacus, also known as red-bellied pacus, bear a striking resemblence to piranhas, and come from the same locale: the Amazon Basin. Same body shape, similar coloration (silver-grey), including the reddish tinge to the ventral area. Pacus are also schooling fish, and reach a size similar to that of the piranha (12"). However, there is one big difference between the two: Pacus eat vegetable matter, such as fruits that have fallen into the water. Because of their large size, they should not be kept in home aquaria unless you have a 200-gallon tank to devote to two or three of them. They are, unfortunately, sold as cute juveniles by fish stores such as PetsMart.
As we watched, the school slowly circled its prey, vigilent to other dangers even while hunting. Without warning they struck, the food gone in a flurry of fins and a flash of silver. There was no hope for that poor fruit, none at all. The pacus slowly swam away, vanishing in the murky waters of the Amazon.