Goldfish are one of the most popular aquarium fishes, especially as a first fish for children, but goldfish ailments are numerous. Goldfish are far from carefree but there are successful treatments for most goldfish ailments. You should start out by doing a little research on goldfish diseases so you know what symptoms to look for in a sick fish, and what sort of supplies you should keep on hand to treat your fish. You should buy a second tank that can be used for any sick fish, and to quarantine new fish for two weeks before placing them in the community tank.