Two species of fish the Carassius C. carassius (Crucian Carp) and C.auratus (Gibel Carp) were recorded in China.  Although there are numerous varieties of Carp and Goldfish, it is possible to trace the origin and the phylogenetic relationship of the major varieties because the emergence of the major varieties was recorded in ancient and modern literature.

The Latin name is  (Carassius auratus) although some publications dispute this. Goldfish were first classified in the genus Cyprinus because of the similarity to the, common carp, Cyprinus carpio. It was later transferred to a different genus, Carassius, and it is now known as Carassius auratus (linnaeus).

Goldfish as we know them did not evolve from the common carp but from the Wild Gibel Carp.  The experts confirm that gold-colored mutants have occurred in both species. The differences between the two have been proven by the morphological resemblances, their chromosome numbers, the lack of barbells, the different rows of pharyngeal teeth, and the key difference between them is the number of gill-rakers: 25-31 in C. carassius and 37-54 in C auratus.

Historians believe that the first appearance of goldfish was in or before the Tang dynasty from records and morphological characters discovered. It is believed that the place of origin of goldfish was the Zhejiang province in China.

After 1189 various colors other than red were recorded. It is thought that the evolution of Gold Gibel Carp could have begun with the change in color from silvery gray to gold and then to other colors. The second evolutionary change was the change in the shape of the caudal fin from the carp tail to the open tail. This open tail (double or paired caudal fin) type appeared after 1506. The open tail is brought about by the forking in the tail skin during embryonic stages. According to the degree of forking, two main types of open tails are recognized, triple tails and quadruple tails. In a triple tail, the upper lobes are fused together but the lower lobes are separated; in a quadruple tail, both the upper and lower lobes are separated.

During the Ming dynasty other mutated characters were discovered and selected by breeding the Gold Gibel Carp: goldfish with protruded eyes called the Dragon-eye, goldfish with dorsal fin and normal eyes called the Wenyu, and the third group is the goldfish without dorsal fin called the Egg-fish. Then during the 18 and 19 centuries the present day varieties were developed. 

There are up to 300 varieties of the Chinese goldfish. The Japanese breed 20 to 30 varieties while the Europeans and Americans also produce some. The Japanese usually name a goldfish variety after the place where the fish is cultivated, while the Chinese goldfish are named according to their special features and colors. 

The earliest history translated says the Wakin and its fantail was bred from the Gold Gibel Carp but it has a short open tail. It is believed that the Wakin ancestor is thought to be the first type of goldfish transported to Japan from China. A prized luxury of the Nippon elite, after two centuries of selective breeding this fan tailed fish became the namesake goldfish of Japan becoming known generally as the "wakin", or the Japanese goldfish.  It is thought most of the fancy fan tailed goldfish have arisen from the original Wakin ancestral mutation.

Even though this breed is the same species as the common goldfish, it is quite different in appearance.  The double caudal (tail) fin is just one characteristic that makes the wakin so unique and especially beautiful when viewed from above in a pond setting.