Titled after Deep Trouble, book #19 of the original Goosebumps series, but based on the plot of Deep Trouble II, book #58.
Billy and Sheena Deep are spending the summer with their uncle, only to discover that fish in the area are growing into giants.
The episode provides examples of:
- Adaptation Name Change: Dr. D's name goes from George to Harold.
- Asshole Victim: Dr. Ritter, as in the book. He stole the plankton formula and used it to experiment on people with, gets an even worse fate — he's turned into a half-human, half-fish mutant, just like the people he experimented on.
- Beauty Equals Goodness:
- Out of Dr. Ritter’s mutant victims, only Luis still looks and talks somewhat like his former human self. He’s also much friendlier than the others; Luis says that the other mutants would hurt Billy and Sheena because they're related to Dr. Deep. Luis is also the only mutant who understands their predicament wasn't Deep's fault. The other mutants are blatantly inhuman with voices to match, and while they aren't technically evil, they’re far less sympathetic than Luis is.
- Subverted with Ritter himself at the end: his mutated form is, if anything, even more humanoid than Luis's. This was probably done so that the show's viewers could still recognize it was him.
- Canon Foreigner: Luis and the other mutated fish people don't appear in either Deep Trouble book. In fact the mutant plankton merely turned humans into actual fish instead of aquatic humanoids.
- Composite Character: Dr. Ritter is Dr. D's assistant, much like Alexander in the first book.
- Slurpasaur: The episode deals with animals being enlarged thanks to Applied Phlebotinum. They use normal-sized iguanas, ants, spiders zoomed in and enlarged with CGI.
