The Curled-gill or Reversed-gill goldfish is another uncommon variety of fancy goldfish that has been developed by specialist enthusiasts. It owes its name from the out-turned appearance of its gill covers.Andrews, Dr. Chris. "An Interpet Guide to Fancy Goldfish", Interpet Publishing, 2002 - Johnson, Dr. Erik L., D.V.M. and Richard E. Hess. Fancy Goldfish: A Complete Guide to Care and Collecting, Shambhala Publications, Inc., 2001 - This fish resembles a Ryukin. For the appearance of this goldfish, it has a fantail-shaped body with long finnage all round as well as a deeply forked tail; the color is typically metallic orange.
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