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 and black pupils.
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 to him to instead of eating keys, he should eat a Krabby Patty.