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.
If your pool or pond has no filtration or aeration, reduce the number still further. Also the larger the surface area of the pool or pond, the more oxygen there will be in the water. The best time to add goldfish to a pool or pond is in early spring after the water temperature has reached 60oF. The water should contain no chlorine or ammonia. Many municipal water companies add chloramine (a combination of these chemicals), which is very toxic to fish.