Ryukin
Ryukin goldfish are compact Japanese fancy goldfish, Carassius auratus, recognized by the pronounced hump rising behind the head and a deep, short body. The variety is associated with fish brought through the Ryukyu Islands, and modern lines may have short, broad tails or long flowing fins. A sharp head, high back, and paired tail give the ryukin a more dramatic outline than a fantail, even though the two can look similar when young. They are produced in red, red-and-white, calico, black, chocolate, blue, and other metallic or nacreous colors.
Compared with many fancy types, ryukins are often strong swimmers, but the deep body still calls for thoughtful feeding and steady water quality. Spacious aquariums or well-managed ponds suit them better than small bowls, and filtration should handle the waste of a fish that can grow thick and heavy with age. Very long-finned examples need protection from fin-nippers and rough decor. The high back is a show trait, yet excessive compression can contribute to buoyancy trouble, so experienced buyers look for a fish that moves level and turns easily. Breeding programs select for the hump, tail symmetry, and a sturdy caudal peduncle.
Colors: Black, Black and Orange, Black and White, Blue, Blue-Gray, Brown, Calico, Chocolate, Gold, Lavender, Matte, Metallic, Nacreous, Orange, Panda, Red, Red and White, Red/Black, Red & White, Tri-Color, White, Yellow