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.

Along Dallas's Trinity River, Jakub Vagner searches for a true Texas titan, the alligator gar. The gar are known for their bony skulls, armorlike scales and piercing teeth, but their natural weapons can't protect them from overfishing and environmental changes. Jakub's mission is to help scientists tag several fish for data and seek out a huge gar to catch and release, hoping to prove that big specimens are still out there. Jakub lands a true behemoth a 125-pound, 6-foot gar!

Jakub Vagner goes head-to-head with a prehistoric fish that survives today the white sturgeon. With a skeleton of cartilage and rows of sharp plates called scutes around its body, a white sturgeon is able to grow to more than 1,500 pounds. However, this extraordinary species has suffered a decline in population because of habitat destruction and overfishing. Jakub joins local experts on a mission to catch and tag white sturgeon to aid the species survival.

A catfish that can weigh nearly half a ton, eat small animals and, rumor has it, even people! Adventure angler and conservationist Jakub Vagner goes face-to-face with the wels catfish in France. He doesn't get swallowed whole, but he does get a vicious bite from a six-foot-long catfish while uncovering the truth about the wels.