Ok, so a lot of people have heard about Insaniquarium. But for those who haven't, just know that it is one of the best computer games ever! It's easy to get to know how to play it, and after a while, can be so addicting. I really know you'll love it.
This is how it works: you start out with some fish. You click your mouse any where in the tank to drop a piece of food to feed your fish. After they start to get bigger, they can start dropping coins, which you can collect to buy products and abilities, such as new fish, better food, etc.
After you get a certain amount of money, you can buy an egg. The egg will have a special creature inside of it that can persom some useful task, such as making new baby fish every so often, or dropping pearls that you can sell for money. So each time you are able to buy an egg, another one of those creatures are added to your tank. And they cannon die.
There is something about this game that makes it so fun, and I'm not really sure what it is. I know you will enjoy it. The graphics and sound effects are pretty good. You can try a free trial first to check it out. Have fun!