Petroleum, a fossil fuel, supplies more energy to the world today than any other source. The United States is the world's leading consumer of petroleum; in 1994, Americans used 7,587,000 barrels of oil per day.
Frequently test for ammonia and nitrite (you want both to measure zero). A pH test is also handy to ensure your goldfish's water is not too alkaline or acidic. This can be purchased at any pet store. Do not modify the fish's water, however, unless it is significantly different from neutral.
When goldfish are in a tiny bowl, they still grow, but much more slowly. It's best to provide at least one gallon of water per full grown fish. This gives goldfish room to swim and explore their home. Plan the aquarium space according to how big the fish can become, not how big he is at the time of purchase.