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.
Goldfish are cold-water fish and can withstand a wide variety of different temperatures, both in aquarium settings and in outdoor ponds. They are compatible with some types of warm-water fish, such as guppies, as long as the aquarist realizes that guppies are much smaller than goldfish and could end up as dinner for ...