River Monsters (2009)

Jeremy Wade travels to Brazil's "wild west" in search of a river monster that has killed three cowboys. The search for the culprit sends him deep into prospecting cattle country, where he discovers the shocking truth about a fish he's never caught before. He has to combat all his fears to catch this monster, and after a long chase, Jeremy finally corners his elusive prey in the most unexpected place. All he has to do then is catch it without getting killed.