I know, they can swim hundreds of kilometers upstream. No other shark is deadlier, would you expect a huge shark in a quiet river if you didn't know any better. They are awesome creatures though.
Edit: these guys are going to give you trouble as well http://www.google.nl/search?hl=nl&rl...vzidfFScu8KNM:
It's a black pacu, a cousin of the pirana, but somewhat bigger.
Enjoy! http://www.google.nl/search?hl=nl&rl...z2NUl4EV7CW2M:
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