Next airing Tue May 1, 2 p.m. ET

Catfish King

Zeb Hogan travels to Spain in search of the invasive Wels catfish -- a monster fish capable of growing more than 8 feet long, eating birds, cats, and, as some legends claim -- even humans! Teaming up with local fishing guides and scientists, Hogan investigates why this voracious predator has flourished in Spain's Ebro River and whether indigenous species have declined as a result.