The catfish is a character who appears in the episode "Code Yellow."
He is a dark green catfish with green whisker-like features and wears a blue hospital apron. He also has orange lips.
Role in episode
He first appears when he has problems in his throat. SpongeBob checks him out and says that he has swallowed his keys. He gets them out by using a sea chicken and suggests eating a Krabby Patty instead of his keys.