Billy has two forms. In his most common form, he is a very short anchovy. He is mainly olive brown, has fuzzy brown hair, and wears glasses. He was also purple and yellow in this form.
In his indigo form, he has long back hair and doesn't wear glasses.
Role in series
Billy is first seen briefly as SpongeBob first enters the prom to join Pearl in the photo shoot. He is seen again along with one of Pearl's friends as her date. Billy's only line in the episode is "Meep."
"The Sponge Who Could Fly"
He appears in the clip of "The Chaperone" shown in the "Remembering SpongeBob" montage.
"Whale of a Birthday"
Pearl and her friends see Billy Fishkins in the mall. They say "Hi" to him and Billy replies with "Meep."
"Suction Cup Symphony"
He is one of the three anchovies playing the violin during Squidward's song.