I accidentally found a cool gadget from aBowman.com. This little gadget allows you to customize the colors of fish, food, and even water. You can also add different numbers of fish. Once you finish customizing your gadget, you can add it to your iGoogle webpage or get the HTML code and paste it on your website.
Feel free to feed my fish by clicking anywhere on the water. The kois will swim to the food. Enjoy!