Piranha Invasion

S4, E6: For centuries the Amazon has been home to a frightening feeding frenzy of the most ferocious fresh-water monsters known to man... piranhas. These fish are said to "mutilate swimmers," their teeth cut through "flesh and bone" and the "blood in the water excites them to madness." Now, these deadly monsters are appearing in US lakes and rivers. The MonsterQuest team is investigating how they may be adapting, and whether these carnivorous beasts could breed here and devastate our waters.