The Fantail Goldfish got the nick named in English that stuck with the variety breed because of what the animals tail most resembles as its most commonly distinct feature to the general human eye.
The fantail is the American breed variety for the ryukin bred in Japan. The breeders who created this variety were trying to create ryukin. As a result, the fantail was developed.
The fantail has a long quadruple fin. They can have telescope eyes or what humans consider to be more natural looking eye configuration and development.
Unlike the ryukin the fins around the body of the fantail are not as developed. They also do not have the pronounced hump that the ryukin are known for.
Narcreous and metallic scales are common.
These fish survive best in water that is from 55ºF to 70ºF. That is a comfort range 13ºC to 21ºC.
Fantails are often orange, red, chocolate (same call it bronze), and calico in coloration.
To arrive at this selected for artistic epiphany goldfish in the fantail line are produced in large numbers ranging into the hundreds if not more to find a breed pair among several generations. This often means breeding grand parents with grand children or other such combination to avoid unwanted features from continuing to manifest in the bloodline. This included the unique take on the egg like roundness of what is now commonly seen as a well bred fantail goldfish.
These fantail goldfish are considered part of the fancy goldfish breeding tradition.