Taking care of fish is more like a hobby than it is owning a pet. Once you set up the tank, there's not much you have to do except to feed them. Maintaining the tank will take about half an hour every two weeks. It's a good idea to read a book or two on the subject before setting up your tank, or at least get advice from an expert at the fish store. Plan on just what kinds of fish you want, and learn what conditions they need to live. Some of the more common varieties for beginners are gourami, barbs, mollies and guppies While fish can adapt to different environments, having to do so causes stress, and can make them less resistant to disease. Try to create an environment as close as possible to the one they live in naturally. Many stores have aquarium sets available that come complete with everything you need, including filters, air pumps, and heaters. If this is your first tank, you might want one of these kits to keep everything simple. Filling your tank is easy if you put a cup in the bottom so the water pressure won't disturb the gravel, then use a hose. Let the aquarium stand for a day or two with the pump, filter, and heater running before adding your fish. When it's time to put the fish in, set the plastic bag with the fish inside into the aquarium water. Leave it there for a while to let the temperature equalize, then release your fish into their new home. Once your aquarium is set up, maintenance consists of occasional water changes to dilute toxic chemicals that may build up over time. Changing about half the water every two weeks should be sufficient. Your pet supply company should be able to provide you with testing kits and other equipment you'll need for this procedure. When you watch your fish swim around, pay attention to their behavior. Sudden behavioral changes could indicate that a disease has made its way into the tank. Antibiotics and other medications are available. See an expert for advice on what to use.