With no pattern to look at, an Ogon is judged on how even the metallic sheen is and how cleanly the scale rows line up. Every scratch, scar and gray patch shows on a solid color, so shipping damage is more obvious than on a patterned koi. Shops split them by color into Yamabuki for gold, Platinum for silver white and Orenji for orange, plus mixed assorted groups.
In the wild
Sawata Aoki created the Ogon in Niigata from a wild carp with golden stripes caught in 1921. He bred the shiniest offspring on for about twenty five years, and two fish finally came out with an even gold sheen over the whole body, usually dated to 1946 though some accounts say 1947. The all over metallic finish is a pond selection, since the wild fish it started from carried only a partial shine.
Good to know
The shine comes from guanine crystals in iridophore cells lying under the scales, and the reflective skin around each scale edge is what keepers call fukurin. Because there is no pattern to segregate, Ogon comes truer from a spawning than the patterned classes do. Crossing that metallic layer into patterned koi produced the whole Hikarimoyo group, including Kujaku and Yamato Nishiki.
Did you know
The metallic classes that followed, from Platinum Ogon to the Hikarimoyo crosses, are all built on the finish Aoki fixed. The founding fish was an ordinary wild carp noticed for a gold stripe, not a bred ornamental. Breeders have since crossed the metallic skin onto ginrin scaled koi as well, giving a metallic body with sparkling scales.
Common questions
Is an Ogon koi a different species from the Koi?
No. An Ogon koi is a variety of the Koi, Cyprinus rubrofuscus, and it wants the same tank, water and food as the species.
What size tank does an Ogon koi need?
An Ogon koi needs at least 264 gal (1,000 L). It spends most of its time in the bottom.
11.8 in (30 cm)119 gal (450 L)39–75°F (4–24°C)
23.6 in (60 cm)317 gal (1,200 L)72–82°F (22–28°C)
6.3 in (16 cm)37 gal (140 L)68–79°F (20–26°C)
5.9 in (15 cm)32 gal (120 L)68–81°F (20–27°C)
4.7 in (12 cm)29 gal (110 L)57–68°F (14–20°C)
23.6 in (60 cm)660 gal (2,500 L)68–79°F (20–26°C)