The Sandbox mode can be accessed after earning either the Silver Trophy or the Gold Trophy from Challenge Mode. Entering the "Konami Code" at the main menu screen will bring the player to Sandbox Mode.
|↑ ↑ ↓ ↓ ← → ← → B A|
While in the Sandbox Mode, players have the ability to spawn any type of fish, pet or alien (excluding Cyrax). Each entity has its own corresponding key in the keyboard.
|"+" and "-"||Rotate Tanks|
The music and backdrop at the beginning will be from the last tank played in Challenge, Time Trial, or Bonus Adventure. If none have been played, Tank 1's music and backdrop will be used. If the backdrop is changed, the music will not change; it will use the last music from the last level played.
- This is the only mode where you can get all kinds of fishes and aliens (also you are still obliged to kill them as they eat or kill your fishes) on any tank other than their introductory tanks. Also, this mode also allowed to get a copy of each pet other than creating a clone of a pet by morphing Presto into another pet and exceed the limit number of pets (maximum is 11).
- You can spawn a Star Guppy without feeding a Star Potion to a large guppy.
- The only fish that cannot be spawned is King Guppy..