Common Name: Ryukin Scientific Name: Carassius auratus Family: Cyprinidae Origin: China/Japan Size: 6 inches Care and Feeding:Does better at the higher end of the â€˜coldwater temperaturesâ€™. While they are omnivores, eating anything editable (although sinking foods are recommended over floating foods).But they can not compete for food against the non-fancy goldfish varieties. Temperature 18-22 C Comments Only keep this fish with other fancy goldfish. Though they can be fine solitary, but they are very social with one another and benefit from having tank mates. While probably the most hardy of the fancy varieties. A nice â€˜starter fishâ€™ into the fancy goldfish sector of the hobby.