More species of fish live in the Amazon River than exists in the Atlantic and Pacific Oceans combined. "The Amazon River has over 3,000 recognized species of fish and that number is still growing....
Piranha electric eelamazonian manateecatfishangelfishbull sharkanaconda snakeorinocobotoetc.
piranha
It would take a full book to cover this subject - the links below will give you a very good start.