While preparing for a reef obstacle course, the kids don't believe that Gush used to be very fast when he was young, because frogfish are so big and slow. However, Gush decides to run the obstacle course just to show them how fast a frogfish can be. / Dunk's "little cousin" Mo, a giant sunfish, comes to visit. The kids try to accommodate Mo, despite his large size, but he's only there for a short time, because large fish like him prefer the space in the open ocean.