Breeder: Oyama
Oyama is a koi farm in the Hiroshima area, south-west of the traditional Niigata breeding country. It is a smaller name than the big Ojiya farms and less written about, but the fish speak for themselves — which is roughly why we buy from them.
Oyama produce Gosanke alongside Kawarigoi, and are associated in particular with Aragoke Ginrin work — heavy, armoured scaling with real presence on a grown fish. We visited on our 2026 trip, and Mr. Oyama explained why his Ginrin keeps its shine as the fish grows when most doesn't, and showed us his Chagoi with metallic pectoral fins: read our write-up of Oyama Koi Farm.
Oyama koi available now
Everything here was imported by House of Koi. We chose almost every older koi individually at the farm, and those are one-of-a-kind: each listing carries video of that exact fish with its size, sex and year born, and closes when that fish sells. Tosai are bought both ways: we pick many out of the pond ourselves, and others come as a mix we chose at the farm, in which case the listing covers a group of young koi rather than one named fish.
Our Oyama selection is metallic and Ginrin: Ginrin Mukashi Ogon, a metallic-finned Ginrin Chagoi tosai, and groups pairing Ginrin Matsukawabake with Ginrin Aragoke Matsukawabake and Ginrin Yamabuki and Kabuto Ogon.
Mukashi Ogon is the old-style metallic — mukashi means "of long ago" — and it is a quieter fish than the modern platinum: a warm, deep metallic sheen rather than a mirror finish. Paired with Ginrin scaling you get two different kinds of reflectivity on the same fish, the body glow underneath and the scale sparkle on top. In moving water it is a genuinely different effect from either one alone.
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