He is a light green fish with black eyes and white hair. He wears a brown rag for shorts.
He meets SpongeBob and Patrick when they arrive in the cave to play Hide and Seek. SpongeBob says "I like it in here. It's roomy" then the Cave Fish laughs. SpongeBob and Patrick think the laugh came from some mice, but they are wrong.
The Cave Fish jumps out and tells them he has been there for forty years. He also says they would all be in the cave forever. The Cave Fish turns SpongeBob and Patrick against each other by telling them the only way to survive is to eat what you could. He says "Eat or be eaten."
At the end of the episode, Sandy reveals herself as the Cave Fish. She gives SpongeBob and Patrick medals to show that they are survivalists. However, the duo, still in a state of hunger, almost eat her.