Most commonly kept aquarium fish.

Do you have an aquarium with goldfish in your house?? How much you about goldfish? The goldfish, Carassius auratus, was one of the earliest fish to be domesticated, and is still one of the most commonly kept aquarium fish and water garden fish. A relatively small member of the carp family, the goldfish is a domesticated version of a dark-gray/brown carp native to East Asia. It was first domesticated in China and introduced to Europe in the late 17th century. There are varieties types of goldfish, however in Chinese goldfish keeping, goldfish are classified into 4 main types, which are not commonly used in the west. Dragon eye - Goldfish with extended eyes, e.g. Black Moor, Bubble Eye, and telescope eye. Egg - goldfish without a dorsal fin. e.g. lionhead (note that a bubble eye without a dorsal fin belongs to this group). Wen - goldfish with dorsal fin and a fancy tail. e.g. veiltail ("wen" is also the name of the characteristic headgrowth on such strains as oranda and lionhead). Ce (may also be called "grass") - goldfish without anything fancy. This is the type that is usually used in Japanese carnivals, especially for "goldfish scoops". Jikin and wakin - goldfish with double tails, but with the body shapes of comets. Some of people believe the goldfish can make their life become wealthy and healthy. However, goldfish is still the famous and beautiful fish.

sources: http://en.wikipedia.org/wiki