The film, as you may recall, involves the opening of a water park, a la Jaws 3-D, which is rudely interrupted by giant, flesh-eating piranhas. And it has a crazy mountain man, played by Bradford Dillman. Watch this film and try not to fall in love with the lunatic hillbilly. He's the main character and he's completely unhinged! When he's not fighting off meat-eating fish indigenous to the Amazon, he's probably mailing explosive packages to government buildings. There's also a nifty bit of stop motion animation when he discovers the secret lab. Yes, Piranha is filled with all manner of glorious, b-movie tropes.
Recently, our own Brad McHargue reported that the Blu Ray release of this fine piece of cinema was due out in April. Sadly, Shout! Factory is now saying that they won't be blessing us with this high-def carnage until August 3rd. I imagine this has more than a little to do with the hopscotch that the Alexandre Aja-driven sequel/remake has been subjected to.
Hi-Def Digest has the skinny here.