Once you have made up your mind and purchased your starter tank, it is time to prepare and start cycling the water to make it suitable to house your pet. Usually a good practice is never to put in your choice of fish that you intend to rare but instead go for low quality “starter fish” like guppy, mollies, platy and swordtail. These starter fish are selected because of their hardy nature, which can tolerate wider range and changes in water parameter and survive the ordeal.
Once the water condition has settled and the nitrogen cycle begins to establish, then only it’s time to put in your favorite fish. If have you purchased a starter fish tank larger than 20-gallon, usually you can choose to setup a community aquarium which houses different types of fish with the same water requirements. But before you do that, check on fish compatibility among individual species that you intend to rare so that you don’t end up losing your precious pets.
You might be interested in understanding about choosing best tank size.