Shiro Utsuri Koi: How to Judge Black and White
Of all the koi that come through our Miami shop, the Shiro Utsuri is the one people stand in front of the longest. Black and white, nothing else: no red to carry the pattern, no metallic shine to distract you. Either the fish has a frame and skin worth looking at, or it doesn't. We like that honesty, and it is the main reason a good Shiro Utsuri is one of the harder koi to buy well.
Here is how we actually look at them, and where ours come from.
What makes a koi a Shiro Utsuri
Shiro Utsuri is a black koi with white patterning, and the most widely bred and refined of the Utsurimono varieties. The black is called sumi, the white is shiroji. Unlike a Kohaku or a Sanke, where the pattern sits on top of a white base, in an Utsuri the two colours wrap around each other in blocks, and the pectoral fins usually carry sumi as well. When the balance is right the fish reads from clear across a pond, which is why so many of our customers buy one as the feature koi they built the pond for.
Body first, skin second, pattern last
That is the order we use, and it is the order koi judges use. Body first: a strong frame, broad shoulders, a smooth taper toward the tail, and a symmetrical body line when you look straight down at the fish. A bent body, uneven shoulders or a weak tail tube is a no for us, no matter how good the pattern photographs.
Skin second. On a Shiro Utsuri the shiroji has to be clean, glossy and luminous, not grey, not yellowed, not patchy. White is unforgiving. A koi with ordinary skin and a brilliant pattern will disappoint you in two years. A koi with excellent skin and an average pattern just keeps getting better.
Pattern last. We know that is backwards from how almost everybody shops, and we say it anyway.
Two words worth knowing while you look. Kiwa is the trailing edge of a pattern; sashi is the leading edge. Sashi tells you about the future, and on a young fish it is normally soft and slightly blurred. That is not a flaw; it is a koi with development still in front of it. And since it comes up: there is no universal A/B/C grading scale in this hobby. If someone hands you a letter grade, ask them what it is supposed to mean.
What a breeder looks at
On a recent visit to Ogata Koi Farm, Yusuke Ogata walked us through a Shiro Utsuri he had picked out to show us, and his checklist was short. For a Shiro Utsuri, he said, it really comes down to two things: the sumi and the skin quality.
- White all the way up. The skin on this fish was really white, and "even the head is really white, which is difficult."
- The head matters. He doesn't like an all-black head. What he liked here was menware, sumi splitting the face, with a touch of black at each eye.
- Balanced, not symmetrical. Zak pointed out there was more sumi on one side. Yusuke's answer: "It's not symmetry, but it's balanced." A fish that is black down one half and white down the other is a problem. Uneven but balanced is not.
- Judge the whole fish. It had a tiny spot of red, which counts against a Shiro Utsuri. But the rest of the fish was good enough that it is easy to forgive.
That fish was a female of Omosako bloodline, with white so clean you could barely see the scales. You can watch the whole conversation below, and the rest of what Yusuke showed us that day, from a finished Showa to his farm's black Budo Goromo, is in our write-up of Ogata Koi Farm.
Buy the future fish
The idea that runs through every farm visit we make applies here more than anywhere: "You're not buying the koi you're looking at, you're buying the future koi." On a young Shiro Utsuri you can often see sumi still waiting under the skin as a blue shadow. "See the blue under the skin? That is the sumi." It may rise over the next few years, or it may not.
"Will the black get better?" We are asked this constantly, and we don't promise it. Sumi develops over years. It rises and sinks, and it responds to temperature and water quality. If you want a Shiro Utsuri whose black is already settled, buy an older, larger fish and pay for that certainty. If you want the ride, buy young and be patient.
The same goes for size. We never promise that a koi will reach a number. Growth depends on bloodline, sex, pond size, stocking, water temperature, water quality, oxygen, feeding, filtration and stress, and any one of those can hold a fish back. Japanese koi can reach 24 to 36 inches and beyond when conditions allow. "Can" is carrying a lot of weight in that sentence.
Where our Shiro Utsuri come from
These are three farms we buy Shiro Utsuri from, and each gives you something different.
Omosako, Hiroshima. If one farm owns this variety, it is Omosako. Their Shiro Utsuri have taken Best in Variety at the All Japan Nishikigoi Show year after year, and the bloodline has spread so far that, as Zak says, "even other koi farms, they say, 'Oh, I have Shiro Utsuri with the Omosako bloodline.'" On our 2026 winter visit we came in at bad timing: they hadn't separated some yet and had sold the rest. So the Shiro Utsuri we chose are being sent on later.
Kaneko, Niigata. A small farm deep in the mountains, run essentially by one man. Zak buys a lot of Shiro Utsuri two-year-olds from him every year. He is also the kind of breeder who will happily spend twenty minutes giving you advice on how to raise and pick koi.
Ogata, Fukuoka. Our Jumbo Shiro Utsuri tosai come from Ogata, on Kyushu, where the warmer climate gives young koi a longer growing season and a head start on size. These are first-year fish bred for size, and the most affordable way into a Shiro Utsuri that could be substantial in a few years.
Tosai or a finished fish?
Both are good answers to different questions. Tosai are first-year koi, and buying them means growing out your own fish and accepting that some will surprise you and some won't. A finished Shiro Utsuri in the 16 to 22 inch range costs more and tells you far more about what you are getting.
Almost every older Shiro Utsuri on our site was chosen individually at the farm and is listed with video of that exact fish, its size, sex and year born. Tosai are bought both ways: many we pick 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. Prices move as stock moves, so check the live listing rather than a number in a blog post. If you are starting young, our guide to buying tosai is the place to begin.
Keeping the white actually white
This is where we see most Shiro Utsuri go wrong, and it is almost never a koi problem. It is a water problem, and shiroji shows every bit of stress a fish is carrying.
The number we care about most is KH, your pond's buffer. Nitrification burns through it, and heavy feeding in warm water drains it for days on end until pH drops suddenly overnight. We want 120 to 180 ppm in a koi pond; anything below about 80 ppm is a red flag. Hard water is not insurance here: GH and KH are separate values, and we see plenty of Miami ponds with hard water and no buffer left at all. Test at sunrise rather than midday, when pH and oxygen are at their lowest. The long version is in what the numbers on your test kit actually mean.
Bringing one home
Quarantine any new koi for at least 30 days, including fish from us. Float the sealed bag 20 to 30 minutes, then add your own water every 5 minutes for about 20 minutes. Never pour the shipping water into your pond. Lights off that first evening, and no food for at least 24 hours. The full process is in our guide to quarantining new koi, and what to do when your koi box arrives covers the first hour.
Then leave the fish alone and let the white come up. A Shiro Utsuri that settles into good, stable water looks like a different animal three months later, and watching that happen is still one of the better parts of this job.
To see how we buy them in Japan, including the Omosako visit, read how buying koi in Japan actually works.
Browse our Utsuri koi for sale: Shiro Utsuri, Hi Utsuri and Ki Utsuri, shipped live anywhere in the USA on Tuesdays and Wednesdays, or picked up free at the Miami shop.
