Last of the Giants - Season 1 Episode 8

Their guides abandon the crew in a hostile area and they must now trek on foot into uncharted territory that exposes them to true danger when they cross stingray-infested rapids, run into an ominous poachers camp and face down armed, angry hunters. Their scientific research is at stake, and the guys are forced deeper into the jungle than ever before to find the 200-pound giant piraiba they need to sample. But with a colossal fish finally on his line, Cyril is in for the fight of his life when he gets dragged into a river full of giant black piranhas.