Vâgner ventures into the world's largest rain forest to go head-to-head with the giant piraiba catfish. These megafish can stretch nearly 12 feet long and weigh a scale-busting 440 pounds. Though mainly preying on other fish, they have been known to eat birds and even monkeys. Local legend even tells of these powerful predators dragging fishermen to the river's bottom! Vâgner endures torrential rain and sleep deprivation to catch this mega catfish of the Amazon.

Vâgner travels in search of the Nile perch in Kenya. This megafish can grow to about 6 feet, 440 pounds, and could be a popular export for the country, except for concerns about a potential parasite that may make the perch dangerous to eat. Vâgner is called in to catch the freshwater beast for scientists to examine and determine if there is in fact a deadly parasite problem. But extreme heat, wind and sandstorms make the journey treacherous and have Vâgner struggling to push on.