Kohaku, Sanke, Showa: distinguishing Gosanke and assessing the quality of their pattern

In a sales tank, three red, white, and black fish swim side by side. Yet two of them have different names and will never be judged in the same way. Gosanke, namely Kohaku, Taisho Sanke, and Showa Sanshoku, are the most sought-after and most frequently confused varieties. To tell them apart, you should not count the colors, but look at where the black is and what it lies on. This guide gives you a side-by-side comparison method, the quality criteria a connoisseur looks at, and what will change in your fish over the years.

Why the Gosanke Dominate Competitions

Gosanke roughly means “the three great houses.” The term encompasses Kohaku, Taisho Sanke, and Showa Sanshoku, which share the same color vocabulary: a white base, deep red (hi), and, for two of them, lacquer black (sumi). Their success comes down to one simple thing: with only three colors, every flaw is visible, and so is every success. A Kohaku with snowy white and thick red, with sharply defined edges, has an elegance few varieties can match.

This requirement also explains their place in Japanese and European breeding programs: these are the most carefully developed bloodlines, and therefore the ones where the price gap between an ordinary fish and an exceptional fish is greatest. For the hobbyist, the stakes are twofold: knowing what they are buying and knowing what the fish will become.

Kohaku: hi on a white background

The Kohaku is the reference variety. White background, red areas, and nothing else. It is described by the arrangement of the red: a Nidan has two areas, a Sandan three, a Yondan four, an Inazuma a continuous zigzag pattern; a Maruten has an isolated spot on the head in addition to the body pattern. Ideally, the red on the head should stop before the eyes and leave the nose white, but tastes evolve and many beautiful fish depart from this standard.

What makes a Kohaku high quality:

• The thickness of the hi: a dense, uniform red, without lighter scales in the middle or a “faded” appearance.
• The shiroji: pure white, without brown spots or yellow reflections. On a Kohaku, it matters just as much as the red.
• Balance: a pattern that runs along the entire length, without a large white gap at the back or an overwhelming mass of red on the shoulders.
• The edges: crisp at the back of the red areas, as if cut with scissors (we will return to this below).

Taisho Sanke: sumi in touches on a white background

The Taisho Sanke, which appeared at the beginning of the 20th century, is based on a Kohaku with black added. But this black is applied superficially, not structural. It is described as ink spots deposited on the skin, mainly on the back, above the lateral line. There are two types: tsubo sumi, placed directly on the white and generally preferred for its crispness, and kasane sumi, placed over the red.

A Sanke's pectoral fins are white or have fine black stripes (tejima). Traditionally, the head has no black. The ideal Sanke gives an impression of lightness: white, beautiful red, and a few touches of black that rhythmically mark the back without weighing it down.

Showa Sanshoku: enveloping sumi and a marked head

Showa are built the opposite way. They are black fish with red and white markings added on top. The sumi is not applied superficially; it envelops the fish: it starts on the back, descends in broad bands below the lateral line, and sometimes reaches the belly. It almost always marks the head, often in a split pattern that the Japanese call menware, and colors the base of the pectoral fins (motoguro).

Older Showa were very dark. Modern bloodlines, sometimes called Kindai Showa, leave much more room for white, making them visually closer to Sanke and fueling confusion. Hence the value of a systematic comparison method.

The 5 points for no longer confusing Sanke and Showa

Place the fish in a clear tank and look at it first from above, then from the side. Review these five points in order; three matches are almost always enough to settle the matter.

In very young fish, the black has sometimes not yet emerged. A juvenile Showa often shows a grayish shadow beneath the skin where the sumi will appear later; Sanke, on the other hand, can look almost like Kohaku during its first few months. When doubt persists, the head and the base of the pectorals remain the most reliable indicators. And a reputable seller will tell you which spawning the fish came from, since breeders sort Showa from the fry stage based on their dark coloration.

Skin quality (shiroji) and edge definition (kiwa, sashi)

Once the variety has been identified, the remaining task is to assess quality. Three concepts come up in every discussion among enthusiasts.

• Shiroji: the background white. It should be pure, opaque, and uniform. Common defects include yellowish white, small brown spots (shimi), and pinkish white that sometimes appears after excess color-enhancing food.
• Kiwa: the rear edge of a red pattern, where the red ends against the white. A sharp kiwa follows the scale pattern like a cut edge; a blurred kiwa “bleeds” into the white.
• Sashi: the front edge of a red area, where the white of the scales partially covers the red. Short sashi is appreciated; very extended sashi may indicate red that is still developing.

For sumi, we look at the depth of the black (a lacquer-like black rather than gray), the sharpness of its edges, and its placement. A fish with fewer colors, but pure white and sharp edges, is almost always worth more than a very colorful fish with dull white. This is the most common mistake beginners make: choosing the reddest fish in the tank at first glance.

Finally, conformation matters as much as color in a Gosanke: a symmetrical body, broad shoulders in females, and proportionate fins. A superb pattern on a crooked body will remain a second-rate fish. For the routine care of these fish, our guide on caring for koi carp covers the fundamentals.

How the pattern evolves with growth

Buying a young Gosanke means betting on a pattern that will change. A few trends help anticipate its development, without ever offering certainty:

• Red stretches with growth. A thin red area on a 15 cm fish may become pale and “transparent” at 50 cm. Connoisseurs therefore look for thick hi in young fish.
• Red can fragment or recede, especially on the head. Red that is already irregular on a young fish rarely improves.
• Sumi develops in many Sanke and Showa: gray areas become black over the seasons. Conversely, early sumi can also fade.
• White reveals itself with age if the water is good; it becomes dull if it is not.

Breeders and enthusiasts often observe that sumi develops faster in hard, cool water, while red benefits from stable water and suitable nutrition. These field observations are consistent with one another, but heredity remains the main factor: two siblings from the same spawning raised in the same water can develop very differently.

Preserve the red and white: water, food, light

A Gosanke will only retain its colors if the foundation is healthy. In order of priority:

1. Stable water. Sudden pH fluctuations, often linked to KH that is too low, dull the skin and stress the fish. Check the KH regularly and correct it if necessary; stability matters more than any precise value.
2. Clean water. Organic matter, nitrites, and high nitrate levels yellow the white and fade the red. Properly sized filtration and regular water changes do more than any additive.
3. A well-reasoned color-enhancing diet. Color-enhancing feeds, rich in spirulina or carotenoids, strengthen the hi. Used continuously and excessively, they can also tint the white. Many hobbyists therefore alternate color-enhancing feed with a basic feed, especially for Kohaku with outstanding shiroji. Our article on Saki-Hikari food explains these formula differences in detail.
4. Controlled lighting. Light promotes coloration, but scorching sun on a shallow pond can mark the skin, especially in fish with unpigmented skin. A shaded area and sufficient depth let the fish choose.
5. A mineral supplement. Montmorillonite clay is widely used by Japanese and European hobbyists. Its effect on the skin is mainly reported through field experience; follow the manufacturer's dosage.

A common case when giving advice: a worried owner sees the red on their Kohaku fading in spring and changes feed three times in one month. The problem was a KH depleted by winter rains and a filter still running slowly. Once the water stabilized, the color returned within a few weeks, without any other change. Always start with the water.

Read also

The pattern accounts for a large part of a Gosanke's value: How to estimate the price of a koi carp?.

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Frequently asked questions

— How can I tell whether my koi is a Sanke or a Showa?

Look at the head and pectoral fins. A Showa almost always has black on the head and at the base of the pectoral fins; a Sanke has a head without black and white or simply striped pectoral fins. The Showa's black also extends below the lateral line.

— What is a koi's shiroji?

It is the underlying white. Good shiroji is pure, dense, and free from spots or a yellowish or pinkish tint. It is a major criterion for all three Gosanke.

— Will a young Showa's black change further?

Most likely. In young Showa and Sanke, the sumi may rise, become denser, or conversely recede over several years. Water, temperature, and genetics all play a role.

— Why is my Kohaku's red fading?

Often due to rapid growth that stretches the hi, unstable or polluted water, a diet low in pigments, or stress. Check the water first before changing the food.

In summary

• Kohaku: white and red, no black. Sanke: black markings on a white-and-red fish. Showa: a black-based fish.
• The head and pectoral fins are the deciding factors: black on the head and motoguro in a Showa, a clean head in a Sanke.
• Quality is reflected in the shiroji, the sharpness of the kiwa, and the depth of the sumi, far more than in the amount of red.
• A young Gosanke's pattern is never definitive: the red and black continue to develop for years.
• Stable water, correct KH, a balanced pigment-rich diet, and protection against sunburn preserve colors.

Last updated: October 3, 2026.