Oh boy, signed my Mermaid Man and Barnacle Boy, now I shall be the envy of the Superhero Fan Club!
Light brown and light yellow
List of characters
Incidental 158 is a light brown fish who first appears in the episode " Prehibernation Week."
He is a light brown fish, with a light yellow dorsal fin. He has black eyes and is usually seen wearing a red T-shirt and a white and blue propeller cap. In some episodes, he can be seen in winter clothes.
Role in series
He is in a super market then when he walks up to
Sandy and then his mother tells him not to talk to squirrels on account of catching their "stupidity."
He is in the
Krusty Krab to use the Skill Crane to win but Squidward mocks him, which prompts Billy to kick Squidward's legs out of anger.
He tries to enter the
Bubble Zoo but SpongeBob stops him and says he is required to smile to enter. He literally then turns his frown upside down and allow him to go in.
He is labeled "kid w/ beanie" in storyboards. 
 In the game , Billy appears with about two color schemes. In some levels, he has his normal color scheme. In others, he is light green with a yellow shirt and a pink beanie.
Drawn to Life: SpongeBob SquarePants Edition