QUOTE
Your fishes tail is that of a good quaility Comet (American shubunkin). The tail of a good quality comet (American shubunkin) is greater that 3/4 of the fishes body length.
To be honest, it's not good quality. Why? It's severely bent and distorted. The length of the tail doesn't always determine the quality.
Ok, I wasn't paying attention to the shape to the tail, just the length. The tail also has to have a good shape to be good quaility.
When I first started keeping fish. The pet stores sold "real" comets. When they had a goldfish tank labled comet it was common to see fish with tails almost as long as the boby. Now days it's common to see tanks labled comet with nothing but common goldfish in it. It's like the pet stores don't know what a comet is any more and the comets that are sold in pet stores don't have the long tails like they used too.