Most fish require limited care. Besides feeding them, the most important thing you can to do for your fish is to keep the tank clean. I like to do a 20-30% water change and vacuum in between the rocks every three weeks. The frequency and the amount of the water change will vary based on the type of fish and the number of fish in your tank. This is the best way to remove the fish feces and excess food that invariable falls into the rocks at the bottom of the tank.

Before purchasing your fish, it's important to determine how large they'll grow in the coming months and years. You may buy your fish at a pet store when they're very young and small, but some fish will grow as much as 10-15 times larger in adulthood. If you have too many large fish in a tank, you're asking for trouble in terms of ending up with a dirty, sick tank. This is a crucial consideration when you're first setting up your tank.

Once you've established your tank, you'll also wan to watch for algae growth. This is a green slime on the aquarium walls and in the water. It can be treated with chemicals or by purchasing a pleco fish for your tank. Plecos get along with most other fish (including aggressive fish) and do a great job eating algae off of the aquarium walls. As an alternative to adding chemicals or buying a Pleco, make sure your tank isn't getting direct sunlight. Sun exposure speeds the growth of algae, so move your tank if this is a problem.

Lastly, you may want to consider getting a water test kit. Test kits can be purchased for a few dollars and will help you determine the quality of the water in your tank. Based on the test results, you'll know what chemicals to add to the tank to bring the water quality into an acceptable range.