Sylvester, the most lowly alien
LGuppy This Article is a Large Guppy
It is complete, but please help it grow into a beautiful King Guppy!

Sylvester is the first alien that you will encounter in Adventure Mode. Sylvester is the easiest alien in the game. He only invades the player's aquarium in Tank 1 and Tank 2. Sylvester can only eat your fishes one at a time. He will get "full" before eating another fish.


Sylvester has a dark blue color, has no visible eyes, has 5 pointed fangs, 3 finger claws and 2 glove blades.


Minisylvester, one of the final bosse's minions

During the Final Boss Fight, Cyrax will spurt out miniature Sylvesters called Minisylvester. He isn't much of a threat, though. Seeing as your laser at that time is Level 8, he only takes one shot.


Minisylvester was created by Cyrax to be a sort of "Yes-Man" or "Toady". Originally he sought to make a Minicyrax, but this plan was disastrous as the Minicyraxes conspired to do away with their creator. Cyrax found the Minisylvesters to be much more malleable to his will... or at least that's what they led him to believe...         


Sylvester used to run a popular sushi bar in downtown San Francisco, but when he discovered a mysterious wormhole that led directly to the Insaniquarium, Sylvester sold the restaurant to pursue his lifelong dream: EATING ALL YOUR FISH!

Virtual Tank

Mini-Sylvester can be bought in Virtual Tank. He is quite rare and grows into his "Adult Form" in a week. Don't worry, he won't turn his back on you! He eats carnivores and in it's "Adult Form" it will eat ultravores. Mini-Sylvester drops Spiral Shells,and Sylvester drops Bag-o-Shells. He can be bought for 15,000 shells.


  • Sylvester is the first alien that you encounter.
  • On the player-created parody, Insaniquarium Deluxe: The Revenge of the Fish, Mini-Sylvester takes the place of guppies of the actual game itself
  • Sylvester and Balrog is only aliens that make similar roars when they appear.
  • Sylvester is the only alien that has no eyes.
  • Sylvester bears a resemblance to a xenomorph.
Community content is available under CC-BY-SA unless otherwise noted.