Leo puts the FishHeads on the case of the Alewife, an invasive species that has become a staple in the diets of larger fish like Rainbow Trout. They begin their investigation in awe of the giant Alewife tornados at Ripley's Aquarium, before venturing to the middle of Lake Ontario with Fishing 4 Tales to learn about fishing and the Rainbow Trout. Christian & Sayat then meet the FishHeads scuba team, who dive deep into the lake to crack the Alewife case!