Piranhas

If cattle are driven into, or of their own accord enter, the water, they are commonly not molested; but if by chance some unusually big or ferocious specimen of these fearsome fishes does bite an animal—taking off part of an ear, or perhaps of a teat from the udder of a cow—the blood brings up every member of the ravenous throng which is anywhere near, and unless the attacked animal can immediately make its escape from the water it is devoured alive.
In popular culture
Hollywood would later emblazon the above gory image for posterity and profit. An example of this perception of piranhas in media appears in the 1967 James Bond film You Only Live Twice, where a piece of meat is shown being fed to pet piranhas owned by the film's main antagonist, Blofeld, then only a bone is raised from the water. Later on, a woman is thrown to the piranha pool, although all that is seen is water bubbling vigorously.