As a hobbyist, many things need to be considered when choosing fish-keeping as your new adventure. First and foremost is the maintenance of the aquarium. Remember, you are controlling your fishes' surroundings - namely the water. Fish are in a limited area that they do not control and they rely on you for a healthy environment. Care must be exercised, as a contaminated tank literally kills. Sufficiently forewarned, let us move on to the other necessities of fish-keeping.
In order to maintain that healthy environment several factors are important. Filtration and water changes of 25% of the water in the tank once a month are very important. Regularly monitoring your pH to ensure the correct level for the species of fish you are keeping is equally important.
As with any hobby you pursue, research needs to be done on the type of fish you wish to keep and the environment they will need you to maintain for them. Books, the web and local fish-keeping clubs will furnish you will excellent information, but by all means do ask questions. Keep in mind that you should select fish that are compatible and require like water conditions.
Suggestions are often given to start out with cold water goldfish as a first choice because they do not need the heat and filtration that tropical fish require. Another excellent choice is a male betta fish (Siamese fighting fish). Tropical fish will require filtration and a steady water temperature of 78 degrees F. This will require a good quality heater and regular maintenance.