Iwashita Koi Farm
by Mamoru Kodama
Iwashita Koi Farm has a display greenhouse two stories high
on the road at the entrance of Mushigame. It has three display
ponds. He breeds mainly Kawarimono such as Goshiki, Kumonryu,
Ginrin Matsukawabake, Doitsu Ochibashigure, Koromo, Doitsu
Goshiki, Ginrin Asagi and so forth.
He is so popular that his place is always
crowded with koi hobbyists in the harvesting season of autumn.
But this greenhouse
is not all he has, of course. He has a breeding farm in a
different place, in the mountains of Nagaoka. The place is
called Tomoto. He breeds Kawarimono as well as Gosanke there.
Reading the trends and demands of the times, he has been
challenged to create a new breed. Policy of Iwashita Koi
When did you start this business?
It has been a while. I think almost 35 years.
35 years!? It is a long time, isn’t it? And you have
always been challenged to create unique varieties. Why is
My goal is to breed an attractive koi that any koi hobbyist
cannot resist. Every year at the harvesting season, Mushigame
always has many koi hobbyists. Even though the store is at
a very good location, at the entrance of Mushigame village,
most of the koi people either used to pass here without making
any stops or give it only a glance. I thought very seriously
about how I could have them stop and stay at my store. I
realized I must have powerful, beautiful and unusual koi
to grab their attention.
That is right. We dealers must have koi that attract customers.
Then, customers would stay and eventually purchase koi.
Yes. So now I breed only fine quality ones of many varieties,
but in small quantities.
What kind do you breed now?
At present, I breed 13 to 15 different varieties including
Gosanke, Ginrin Matsukawabake, Asagi, Ginrin Asagi, Goshiki,
Kin Kikokuryu, Heisei Nishiki, Kumonryu, Utsurimono, Gin
Matsuba, Aka Matsuba, Doitsu Showa.
Do you breed them all by yourself?
No. I cannot breed them all by myself. I leave some of my
breeder koi with my relatives who live in the same village
and have them breed those.
Is there any particular variety you do not breed?
I do not breed Platinum. It is because I cannot breed good
Platinum at my farm. For some reason, they have red on their
I see. Now tell us a little about your ponds.
My place in Nagaoka is about 2.5 acres with 28 ponds and
2 large mud ponds. I have had them since 1982. I use 12 ponds
for tosai. In autumn, I harvest 5000-6000 and keep 3000 in
a greenhouse. Many breeders in Niigata have large mud ponds,
but I think the size does not really matter. Ponds that you
can easily manage and maintain are more important in breeding
I agree. Ginrin Asagi is one of your representative varieties.
Can you talk about your famous Ginrin Asagi? What made
you decide to breed this variety?
It is always out of curiosity and with one simple question:
what would Asagi look like with ginrin?’ I was lucky.
When I posed the question, I came across a male Asagi that
had ginrin by accident! I crossbred this male with a female
regular Asagi. Getting the male Ginrin Asagi, instead of
a female Ginrin Asagi was the secret of success. It raised
the ratio of beautiful ginrin. appearance so much.
That sounds interesting. As a result, you finally stabilized
and completed the variety of Iwashita Ginrin Asagi that
made you famous.
Yes. It was in 1999.
How many of them do you breed now?
I have bred Ginrin Asagi every year since then. Naturally
I keep only good ones after several cullings. Eventually,
only about 1000 meet my standard and remain. I sell half
to Japanese customers.
In other words, another half, which is only about 500,
is available for hobbyists outside of Japan. This is
premium variety, isn’t this? What is the most difficult
part in breeding Ginrin Asagi?
The most difficulty absolutely lies in that good ginrin is
very unlikely to appear on Asagi. Because ginrin is genetically
strong, varieties like Kohaku, Taisho Sanke, Showa can easily
have good ginrin. But that is not the case in Asagi variety
for some reason.
I see. How about the hi?
Yes, they are difficult, too. Having brilliant hi on the
pectoral fins, belly and yakko (cheeks) is an important factor
for Asagi's beauty. But only 30% of the productions have
the hi. This makes the breeding of Ginrin Asagi even more
This is why you can have only 1000 or so. But after severe
culling, your Ginrin Asagi is definitely one of a kind
with quality and beauty. They win top awards even at the
All Japan Nishikigoi Show.
Yes. They often win at the category of B Ginrin in All Japan
Nishikigoi Show. B Ginrin is the category for all the ginrin
varieties except Gosanke. So I think it is quite a tough
competition and quite an honor for my koi to win at such
How about Goshiki? You have a wonderful parent for Goshiki.
She is 10 years old now. The stepped pattern is beautiful.
When she was 3 years old, she already showed excellence.
One customer was very eager to obtain her and offered me
$5,000. But I wanted to breed beautiful Goshiki like this
by myself. It was my dream. So I decided not to sell her
and to keep her as a parent.
And you made a right decision.
I think so. Goshiki is a variety that has a Kohaku pattern
on the Asagi background. And it is important in breeding
Goshiki that the hi color is beautiful. Its hi design must
be well-arranged and the hi quality must be high. Because
the parent has such a high quality hi and superior hi pattern,
the offspring won top awards at All Japan Nishikigoi Shows
and proved itself for the supreme quality. It is common sense
but still true that parents must be exceptional to breed
high quality koi. This Goshiki has excellent hi quality and
coloration. When she was 2 years old, sumi appeared on the
hi a little bit. But as she grows and hi gets enhanced, the
hi stands out as if it is emerging. That is the character
and attractiveness of my Goshiki.
Ginga that you made is the variety that has ginrin on Matsukawabake,
Yes. The idea also came from a simple question: ‘what
would happen if Matsukawabake has ginrin?’ The difficult
part was what to use as parents to breed this Ginrin Matsukawabake.
So tell me what did you use?
The female parent was from a crossbreed of Kumonryu and Shiro
Utsuri. And the male parent is Ginrin Matsuba out of Ginrin
Ochibashigure, which looked very black, almost like Karasu.
What is the difficulty in breeding this variety?
It is in the culling of fry. Though they have ginrin, most
of them are Chagoi. Naturally it has the blood of Ginrin
Ochiba Shigure as its ancestor; most of the fry are brown.
Among the Chagoi, I select ones that have strong black and
strong ginrin. And when they are Tosai, the whole body becomes
black. Then as they grow, they start exposing shiroji (white
background) like Matsukawabake and the ginrin stands out.
It is not too exaggerated to say that almost all of the fry
are dirty and not worth keeping.
It must be really difficult to decide which to keep and which
Absolutely. Experience and intuition really count in deciding
which to keep. What I learned from breeding many Kawarimono
is to raise them until autumn no matter how dirty they look.
Believing when the bloodline is good, they should expose
their potential beauty as they grow. So, I breed them carefully
and patiently. Of course, it is essential that they must
have qualities such as sumi and ginrin to be selected.
Thank you very much for your time today. Please
keep up your great work. I am sure every koi hobbyist in
the world looks forward to have your koi in their pond.