There are several species in the genus Serrasalmus and their ferocity appears to depend on the size of the school. In the Paraná River the schools run to hundreds and even thousand and the individuals are more agressive. In Guri Reservoir, Venezuela, the species forms school of a dozen or less and the fish are less aggressive people swim among them and catch them for food. I had a friend who suffered a serious bite removing hook from one, however. Like sharks, they respond to chemical stimuli of blood in the water and may develop a feeding frenzy. The most feared species is S. natteri, in southern waters.

there's little evidence that a dinosaur has ever killed or eaten a human either, yet it's all over the movies.

Just google piranha attacks and you will find documentation of piranha attacks. If piranha can attack cows why not people. Teddy Roosevelt encountered them on his travels and witness a cow being eaten by piranha. Just because there are not records of it does not mean it does not happen. South America barely keeps birth records let alone piranha attacks or other attack.

Look, this movie is pure fantasy, i mean they use prehistoric piranha so you couldnt even compare the two. As far as attacks on people, there have been alot of here-say quotes about them attacking "distressed" animals and people.. So if per say a human that could not swim well was to fall in the water their flailing and distress could cause them to attack. But as the article says they can be very skitish and prefer meals that dont move allot.

More than anything else in the grand scheme of everything, "Piranha 3D" is unfair to the humans who are attacked randomly by its movie previews on late night television, for sure . . .

For sure!

And while I have no specific evidence that piranhas have attacked living human beings, I do recall a recent program on one of the science channels that had a segment about piranhas and showed a group of people who lived in houseboats on the Amazon River (or someplace), where the locals at least suggested that swimming in what for them was their "backyard" was not the brightest idea . . .

Yet, overall I think the general concept is good for the betterment and enlightenment of others, since the fact of the matter is that humans are not designed for swimming or dwelling in water, and there certainly are a lot of gnarly things that live in water (briny, fresh, and salty), which also is the case with mud, where as recently as the past few weeks it has been revealed that there are tiny wormy parasites that live in the dirt and mud in the Appalachian region of our great nation and apparently routinely cause parasitic diseases in unsuspecting gardeners and other folks who wander amidst the dirt and mud with bare hands and feet . . .

And all the more recently, there are beginning to be somewhat regular news reports on "kissing bugs" (triatomines) that in addition to being vectors for Chagas disease, apparently have bites that cause life-threatening allergic reactions for some people . . .

http://bodyodd.msnbc.msn.com/_news/2010/08/20/4904714-sweet-sounding-kissing-bugs-can-take-your-breath-away

http://en.wikipedia.org/wiki/Chagas_disease

For those folks who are intrigued by interesting medical signs--where "signs" in this context refers to factual things that someone else can observe (objective) as contrasted to "symptoms", which are subjective and only can be observed by the patient--the classic medical sign for early Chagas disease is the Eye Sign of Romaña, which is a swelling of the upper and lower eyelids that looks a bit like a "black eye" but without the discoloration and bruising . . .

And while Chagas disease is more of a problem in Mexico, Central America, and parts of South America, it is becoming a problem in the Gulf Coast region of our great nation, since among other things it is a tropical and subtropical disease which is associated strongly with dwellings in muddy areas, as well as adobe and similar types of building materials . . .

For reference, the way I learned about Chagas disease was by doing a bit of web surfing to identify a bug I found inside the house, and I was not a happy camper when I found the photograph of a "kissing bug" and started reading about it, even though the nearest Gulf Coast beach is at least 100 miles from here, really . . .

Really!

From my perspective, the best hypothesis is that hurricanes Katrina and Rita blew a lot of insects inland from quite a few locations, as well as moving a lot of otherwise local insects somewhere else (mostly bees and butterflies), although the entire bee thing has been pretty strange for at least a decade, where over the past few summers seeing even one bee has been a rare event, as it has been for butterflies . . .

When I was younger over half a century ago, there literally were flocks of butterflies and honey bees, but these days it is a bit unusual to see even one butterfly or honey bee, which among other things is the direct consequence of the patently evil Frankenchemicals and Frankenplants that are created and marketed by Bayer CropScience, Dow Chemical Company, DuPont, Monsanto, and so forth in their concerted efforts to transform every living thing on the planet into a strange and bizarre mutation . . .

If the folks in Hollywood want to do a truly frightening motion picture that is based on scientific facts and realities at the dawn of the early-21st century, then the most obvious title is "Frankenfood 3D", which among other things features Frankensactors and Frankenactresses from virtually the entire beverage, bread, candy, dairy, dessert, fresh fruit, highly-processed frozen food, insecticide, meat, pesticide, snack, and vegetable sections of every grocery store in our great nation, for sure . . .

For sure!

As someone who spent two years working with a Marine Biology team from Stony Brook University, I have to say I dislike the idea of any movie that could cause people to "prove their manliness" by fishing a species to near extinction, as was the case after Jaws. However, given the current politics in AZ, seeing people from that State get eaten alive does bring a smile to my face. Karma's a bitch!

Alan,

You are one great big wet blanket. :-)

Bikini clad beauties in 3-D? That sounds like summertime movie bait to me.

Did you say there were fish in this 3-D Bikini movie?

Oh...hahaha...I get it....fish....bait....hahaha, very funny,

but you are still a wet blankey