Various artists.   From director Alexandre Aja (The Hills Have Eyes) comes the new action thriller PIRANHA 3D. Every year the population of sleepy Lake Victoria explodes from 5,000 to 50,000 for Spring Break, a riot of sun and drunken fun. But this year, there's something more to worry about than hangovers and complaints from local old timers; a new type of terror is about to be cut loose on Lake Victoria. After a sudden underwater tremor sets free scores of the prehistoric man-eating fish, an unlikely group of strangers must band together to stop themselves from becoming fish food for the areas new razor-toothed residents.