Carassius auratus is a freshwater fish of cyprinida e, cyprinida. It is one of the most commonly raised aquarium fish.

Goldfish are relatively small members of the carp family (including the Prussian carp and the fish), native to East Asia. It was bred selectively in ancient China more than a thousand years ago, and several different varieties have been developed since then. Goldfish species vary greatly in size, shape, fin structure, and color (various combinations of white, yellow, orange, red, brown, and black are known).

As of April 2008, the BBC believed that the world's largest goldfish was 19 inches (48 cm) long and lived in the Netherlands. At that time, a Goldie was kept as a pet in a tank in foxtone, England, measuring 15 inches (38 cm), more than 2 pounds (0.91 kg), named the world's second largest fish behind Dutch fish. "I think there may be some bigger goldfish, people may not think they are record holders, maybe they are watching lakes," the Secretary of the Federation of British aquatic associations (FBAs) said of Gordy's size In July 2010, a 16 inch (41 cm) and 5 pound (2.3 kg) goldfish was arrested in a pond in Poole, England, and is believed to have been discarded when the tank grew up.

Goldfish live in groups, not only showing school education behavior, but also the same type of feeding behavior. When goldfish react to reflections in the mirror, they may behave similarly.

Goldfish have learned that both as a collective and as an individual originate from the behavior of local carp. They are versatile species with different feeding, breeding and avoiding predatory behaviors that contribute to their success. As fish, they are "friendly" to each other. Goldfish rarely harm other goldfish during breeding, and males do not harm females. The only real threat goldfish face to each other is fighting for food. Ordinary food, comets and other faster varieties can easily eat all food during feeding before they can be eaten. When they are raised in ponds with one tailed brothers, this can lead to stunting and even starvation. Therefore, it should be noted that only the varieties with similar body shape and swimming characteristics should be combined.