Mr. C.B.  Brown in his work on Guiana gives the following account of this fish: 

The piranhas in the Corentins were so abundant and were so ferocious that at times it was dangerous to go into the water to a greater depth than the knees.  Even then small bodies of these hungry creatures would swim in and make a dash close to our legs, and then retreat to a short distance.  They actually bit the steering paddles as they were drawn through the water astern of the boat.  A tapir which I shot as it swam across the water had his nose bitten off by them whilst we were towing it to the shore.  The men used to catch some of them for the sport of it, and in taking the hook from the mouth produced a wound from which the blood ran freely.  On throwing them back into the water in this injured condition, they were immediately set upon and devoured by their companions.  Even as one was being hauled in on the line, its comrades, seeing that it was in difficulties, attacked it at once.

I heard about these fiends but had no opportunity to witness their ferocity until one day, in crossing the river in a dugout, we wounded a wild hog that had also decided to cross at the same time and at the same place.  The man with the stern paddle seized his machete as he saw the hog swimming close by the port-side of the canoe and stabbed it in the shoulder, intending to tow it ashore and have a luxurious dinner of roast hog.  But his dream was never realised, for the piranhas which had tasted the blood, I suppose, came in large numbers and set upon the unfortunate hog.  In a minute the water seemed to be boiling, so great was the activity of the little demons as they tore away pieces of the flesh until it was vanishing by inches.  When we reached the other shore there was not enough left of the hog to furnish a single meal.

Later I learned that certain Indian tribes leave their dead in the river for the piranhas to strip the flesh from the bones.  It is then customary to take the remaining skeleton and let it dry in the sun, after which it is rubbed with the juice of the urucu plant (the Bixa orellana), which produces a bright scarlet colour.  Then it is hung up in the hut and the Indians consider that a token of great reverence has been thus bestowed on the deceased.

Before leaving the subject of fish, I will mention another species, smaller than the piranha, yet, although not as ferocious, the cause of much dread and annoyance to the natives living near the banks of the rivers.  In fact, throughout the Amazon this little worm-like creature, called the kandiroo, is so omnipresent that a bath-house of a particular construction is necessary.  The kandiroo is usually three to four inches long and one sixteenth in thickness.  It belongs to the lampreys, and its particular group is the Myxinos or slime-fish.  Its body is coated with a peculiar mucus.  It is dangerous to human beings, because when they are taking a bath in the river it will approach and with a swift powerful movement penetrate one of the natural openings of the body whence it can be removed only by a difficult and dangerous operation.