|This article is a guppy. Please help it grow into a King Guppy.|
The Star Potion is a Food item and can be bought for $250 in Tank 2. If a Large Guppy swallows one, it will turn into a Star Guppy and will produce Stars (worth $40) instead of Gold Coins (worth $35). However, if a Small or Medium Guppy attempts to eat the potion, the potion will explode and the Guppy in question will die, and you would have wasted your money to kill your fish. This does mean a Star Potion can be used to deal large damage to Gus, who cannot be damaged by Laser Guns.
It's best to use these to turn a decent amount of Guppies into Star Guppies, and use them in conjunction with the Starcatchers, as they will turn the Stars into Diamonds, making the $5 profit from Gold Coins to Stars into a $165 profit from Gold Coins to Diamonds. However, one must be careful with how many Starcatchers there are in the Tank, or else there may be more than can actually be feed. A good balance would be about 3 Star Guppies per 2 Starcatchers.