Genetic research has shown that the goldfish actually derives from the Prussian carp Carassius gibelio.

Prussian carp (Carassius gibelio)

Goldfish (Carassius auratus) and Prussian carp (Carassius gibelio) are now considered different species.

Goldfish (Carassius auratus) were originally domesticated from the Prussian carp (Carassius gibelio), a dark greyish-brown carp native to Asia.

Carp were first bred for color mutations in China more than a thousand years ago, where selective breeding of the Prussian carp (Carassius gibelio) led to the development of the goldfish.