FishVille

FishVille is an interactive fish tank on Facebook. The player can buy fish and grow them. Individual fish have levels which are increased when they are taken care of properly. The player also has a level which earns access to additional features and certain items. Like other Facebook games there's two types of currencies: one which comes in abundance as long as the player comes back to the game regularly and one currency which is rare but can be bought for actual money. The currencies can be used to revive dead fish, buy fish food and items to decorate the tank.

It's also possible to visit friends and earn additional experience points and money while visiting. There's a treasure chest in the fish tank that gives a bonus every hour (if clicked) and it's possible to send gifts to friends on Facebook.