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.
There are many kinds of goldfish. The most common kind is golden-colored, but goldfish come in many different shapes and sizes. Many gold fish have fancy tails. Another common kind is called a black moor, which is black colored. Wild goldfish are called prussian carp and are silver-green in colour.