Cave Fillet is the last stage in Sea of Tuna.
The Enemy's castle will spawn 2 Those Guys.
If you are trying for 3 stars difficulty, remember that Teacher Bun Bun is now 12 times stronger than normal! If you don't bring enough meat shields (4 is recommended), you will be wrecked easily.
This level requires some luck, in particular if you don't have any True Forms/Crazed Units. Delinquent Cat and Bodhisattva Cat can be great help, as they can help stall the movement of Teacher Bun Bun. More meatshields also help as this level, when close to your base.
If you want to use sufficient long-range attackers, sending out constant waves of meatshields is crucial. If the constant wave of meatshields are not constant, Dark Emperor Nyandam may move up and kill all of your long-range attackers in one hit. If you have Megidora, it'll help you a lot, so be sure to level him up as much as possible.
Also do not bring any cats that knockback floating enemies! If you knock back Bun Bun, all of your units will get into the range of Nyandam and get killed.
It is recommended to buy Boogie Cat at this point, because without 2 or more meatshields, the upcoming stages are very difficult. If you do not wish to use cat food, try to get cats from event stages like Faster than Fast Food or any stage of All Hallow's Road.
Strategy for 3 stars level
Use 1 of Crazed Wall Cat to slow down the Those Guys. Once the Crazed Wall dies, send another one. Keep this until you have maxed worker and maxed money. It's not recommended to stack up Bahamut Cat at the time, because the rate Those Guys comes out is too slow. Then put in all the cat you've brought. It is recommended to have Paris Cat, Dancing Flasher Cat, Crazed Macho Cat, Crazed Wall Cat, Crazed Bahamut Cat and any Uber rare you have. (PS: I have used The Majestic Zeus and Super Galaxy Cosmo.)