Encyclopedia SpongeBobia
Encyclopedia SpongeBobia
Not to be confused with Incidental 23 or the Male cowfish.
Well at least I still have my personality.
— Incidental 31, "Prehibernation Week"

Incidental 31, also known as Blue Fish and Blue Castaway, is a fish who first appears in the episode "Ripped Pants." He is classified as a "inbetween" type incidental.[1]


He is a cyan fish with three dark blue stripes on his back, light blue fins and a unibrow. He wears red swimming trunks.

Blue Fish

He is a blocky looking 3D video game model of Incidental 31's normal variant.

Blue Castaway

He has a thinner body structure and he wears a brown rusty divers helmet and has no swimming trunks.

Role in series

Incidental 31 at the Krusty Krab.

Incidental 31 is a somewhat common incidental character, he has had many notable & speaking roles as well as minor and non-speaking roles. He was firstly designed to be a beachgoer.

Major roles


He orders a Krabby Patty with extra onions at the beginning of the episode.

"Hall Monitor"

He appears as a student at Mrs. Puff's Boating School where he is shown with a bored expression shown on his face near the beginning and the end of the episode.


He and Incidental 23 spit their food out before all the customers freak out from hearing Mr. Krabs saying he doesn't want SpongeBob sneezing all over his food.


He, Fred, and Incidental 9 act difficult with Squidward as the fry cook at the Krusty Krab.

"Something Smells"

He is seen standing in the Reef Cinema bathroom with Incidental 30 and Incidental 41 where Patrick offers to tell the three of them a bathroom joke but they quickly get disgusted by his rancid breath and Incidental 31 calls out "You tryin' to kill us!" before the three exit the restroom.

"Patty Hype"

He, Incidental 42, and Incidental 5 show Mr. Krabs their colored tongues that they got from their pretty patties.

"Grandma's Kisses"

He is one of the customers at the Krusty Krab that constantly make fun of SpongeBob getting kisses from his grandma with Squidward. He is also seen with Squidward at the end of the episode laughing at SpongeBob's crying at Grandma SquarePants' house.

"Prehibernation Week"

While looking for SpongeBob in a sulfur field, he pokes his head into a crater and is burnt by a burst of sulfuric gas. Even with his charred, disfigured face, he claims at least he still has his personality. He later tries to pass SpongeBob off with a Kelpo cereal box to Sandy, but fails.

"Band Geeks"

He and Mrs. Puff are seen smiling behind SpongeBob during his speech about helping out Squidward.

"The Bully"

He is seen as a student in Mrs. Puff's Boating School where he is shown to acknowledge the sounds of SpongeBob rearranging his pencils at the beginning of the episode. He also literally puts on a happy face when Mrs. Puff tells the students to put on a happy face for Flats the Flounder.

"Krusty Krab Training Video"

SpongeBob runs through his and Incidental 45's table during the emergency situation part of the training video.

"Pranks a Lot"

He appears at the Krusty Krab sitting at a table with Squidward, happily watching a naked SpongeBob and Patrick.

"Krabs vs. Plankton"

He is part of the jury.

"Fungus Among Us"

He bites into an Ick infected Krabby Patty.

"Krabs à la Mode"

He orders 2 frozen Krabby Patties to use as skates.

"Slimy Dancing"

He becomes sick and throws up from watching Squidward do ballet from inside SpongeBob during the show.

"Pest of the West"

He is one of the cowboys at the Krusty Kantina singing "Dead Eye" with Pecos Patrick.


Squidward is seen taking his order at the Krusty Krab while Mr. Krabs was talking to SpongeBob on the phone.

"Sand Castles in the Sand"

After Patrick gets sand in his sandwich, Incidental 41 laughs and jokingly tells him that's why they call it a "SANDwich." Incidental 41 then chokes on some sand.

"Model Sponge"

He is part of the action crew for the New Sponge commercial, announcing the first take of the commercial with a movie clipboard.

"Krusty Dogs"

He, Incidental 47, and Incidental 92 become unamused by SpongeBob trying to convince the customers to stop eating Krusty Dogs while dressed as an old timely gentleman. They later notice Incidental 41's Krusty Dog about to explode and it explodes all over the three of them.

"Free Samples"

He gets food poisoning from trying a Krabby Patty made out of chum by Plankton.


Mr. Krabs is seen taking his order while he was running the Krusty Krab by himself.

"Move It or Lose It"

He purchases Plankton's riptide generator from his yard sale.

"Squid Baby"

SpongeBob tries to change baby Squidward's diaper on the Krusty Krab floor but Incidental 31 tells him that he is trying to walk here.

"Little Yellow Book"

He is seen swinging on a rope in the Krusty Krab with other ravenous customers and then becomes amazed when he and Incidental 41 receive their Krabby Patties from SpongeBob.

"Tutor Sauce"

He is seen driving a gasoline truck down a one way street where he crashes into the Krusty Krab due to SpongeBob driving the opposite way. This also causes the Krusty Krab to explode.


A sleeping Incidental 31 is seen as one of the impatient customers forming a line at the Krusty Krab.

"Mutiny on the Krusty"

He is a customer at the Krusty Krab during the current. He tries to exit the Krusty Krab but a security buzzer goes off due to still having money on him. Mr. Krabs forces him to spend more money but he claims that he needs the money for rent.

"Mustard O' Mine"

He appears as a surfer miner with Incidental 23 and Incidental 41.


He is the first customer to be insulted by ChefBob. At first, this causes him to blush in embarrassment but he soon finds it funny and laughs along with everyone else.

"Squid's on a Bus"

He is a passenger on the bus that was being drove by Squidward.

"A Place for Pets"

He drops his pet clam off at the Krusty Krab and asks Squidward if he could get him a Krabby Patty, but Squidward tells him only pets gets patties and tells him to eat at the Chum Bucket. Incidental 31 claims he doesn't want to eat at the Chum Bucket as he sadly walks over to the restaurant.

"Upturn Girls"

He is seen eating at the Krusty Krab at the of the episode where he gets disturbed by SpongeBob scrubbing the inside of his chair while Pearl delivers him a wrongly made Krabby Patty. Narlene then comes out from inside his chair to greet SpongeBob and after Narlene has Pearl shake her foot with saliva on it, Pearls wipes the saliva on Incidental 31's back, much to his disgust.