Nugget, a minnow, does everything with his best friend Fang. Everything except go to Minnow School. Sharks aren't allowed at Minnow School, and Fang is a shark.
At Minnow School, Nugget learns all about how terrible and horrible and awful and just plain bad sharks are. Nugget thought that his friend Fang, a shark, wasn't any of those things - he is a great friend... but his teachers and his homework wouldn't be wrong, would it?