What Fish Can I Have?

If you are a beginner aquarist, it's best to start with a freshwater aquarium as opposed to a salt water aquarium or a reef tank. Although it can be tempting with all the beautiful saltwater species and corals available, a freshwater tank is easier to maintain and also a lot less costly to set up.
When choosing your fish you have to consider how big they'll get. When they're little you just want to put a whole school of them in your tank! At least I did... and it was a big mistake.
The rule you'll most often hear about is an inch of fish per gallon of water. However, full bodied fish such as Goldfish, require a lot more space. You must also take into account the shape of the tank, as the air exchange happens at the surface of the water. A tall thin tank has less surface area for the volume of water than a short long tank.
I will put together a comprehensive list of all the different kinds of available fish, their requirements, and their potential tankmates.

Check back often as more fish are added to the list.