He is a short fish who wears a blue tie, a light blue shirt, and reddish-brown pants (blue pants in "What Ever Happened to SpongeBob?"). He works for the Bikini Bottom Department of Health and appears to be inexperienced at his job, as he does not care if he is not doing it properly.
He appears in New Kelp City as one of the people waiting outside of Games We Play, and gets scared when CheeseHead BrownPants blows a bubble. After CheeseHead defeats The Bubble Poppin' Boys, Carl is one of the citizens that celebrates by blowing bubbles, and he later attends CheeseHead's speech after he becomes mayor.
He is one of several customers that SpongeBob can deliver food to.
Squidward calls the health department to file a complaint against SpongeBob's Place, prompting him to come the next day.
Carl and Health Inspector Yellowtail arrive at the restaurant near the end, as it is illegal to sell food inside pineapples. However, Carl does not care about city health codes and eats a Krabby Patty from SpongeBob's Place, prompting Yellowtail to toss the patty and remind him about the laws. Carl scornfully walks off, falsely stating that Yellowtail is not the boss of him.
He is one of the many jellyfishing fans who travels to Hotel Halibut for the 36th Annual Jelly-fisher Convention.