There are several elements to consider when creating and maintaining a fresh-water aquarium. First, though aquariums are available in various shapes, a rectangular one is advantageous because it allows the most oxygen to reach the fish. Gravel or pebbles can be used to line the tank, and either live or artificial plants can be added. Additional structures should also be added to provide shelter and security for the fish. Tap water can be used in the tank, but it should be soft and neutralized of its chlorine. In addition, a consistent temperature should be maintained by using a water heater and thermometer. An aerator pump and a filter system should also be installed to ensure well-oxygenated water and the removal of solid and chemical wastes from the water. Once installed, an aquarium almost never needs to be cleaned. Aeration, filtration, occasional water changes, and scavenger fish should keep the aquarium well maintained. For more information on aquarium maintenance, consult a pet store or veterinarian in your area.