Jason, Zack, & Trini go scubadiving. Billy's invited, but this just brings up bad memories from his childhood. Seems as a boy, he was playing in a lake, when a fish bit his finger. Since then, he's been quite afraid of aquatic animals. Rita exploits this fear, sending down the Toxic Goo-Fish monster. Blue Ranger manages to overcome his fish phobia, and filets the villain.
