The Butterfly tail (Man Shek-hay, 1993) or Butterfly telescope (Teichfischer, 1994) is a variety of goldfish that is distinguished by the butterfly-shaped caudal fins when viewed from above. It is a variety that has only recently been deemed a major lineage by a few published works. Because this tail conformation is commonly bred into the telescope eye goldfish, the term "butterfly tail" is just short for the many names this variety has such as Butterfly Tail Telescope, Butterfly Tail Demekin, Butterfly Tail Moor and Top view Telescope (TVT).
The butterfly tail is a variant form of the telescope goldfish with protruding eyes and is best appreciated by viewing it from above. While this tail variation is commonly paired with the telescope eye variation, 'butterfly shaped tails' may be present in other goldfish standard varieties such as ryukins or orandas. The tail spread is preferable 180 degrees but some may droop down at an angle due the weight of the long tail fins. With the rise in popularity of butterfly tail moors, there have been efforts to distinguish the different butterfly tail types such as the faery butterfly, shuan shu (Chinese comb tail) butterfly, delta and trapezium tail butterfly.