Kujaku: Complete Variety Guide

1. What is Kujaku?

Kujaku is a metallic, patterned koi with an Asagi-like dark net or mesh effect over the scales and red-to-orange markings laid across a bright metallic body. The All Japan Nishikigoi Promotion Association describes Kujaku as a variety produced on an Asagi foundation, with Hikari-moyo characteristics and red markings added through selective crossbreeding. The association also notes the alternative name Kujaku-ogon.

In practical terms, a typical Wagoi Kujaku combines four things: a sound koi body; metallic lustre over the entire fish; organised dark reticulation associated with the scales; and a balanced hi pattern. None of these components should be judged in isolation. The finest fish make them appear integrated rather than layered on top of one another.

2. Why Kujaku is called the “peacock” koi

The Japanese word kujaku means peacock. The name is not a literal description of peacock colours; it refers to the ornate, shimmering impression created by metallic skin, scale pattern and coloured markings. Under strong but even lighting, a good Kujaku can display changing silver, platinum, bronze and red highlights as the fish moves, giving the body a decorative richness unlike a non-metallic koi.

That visual drama should not be confused with quality by itself. Strong glare can hide defects. Evaluation is best done from several angles and, when possible, under softer daylight as well as direct bowl lighting.

3. Official definition and current classification

The Japanese Agricultural Standards material presented by the All Japan Nishikigoi Promotion Association defines Kujaku as having an Asagi-like pattern, scarlet markings on the back and metallic shine across the entire body. That definition is useful because it emphasises all three identifying elements: netting, red pattern and whole-body lustre.

Under the current Zen Nippon Airinkai variety system, Kujaku is shown within Hikari-moyomono, the Group 2 class for metallic koi with two or more colours other than the Utsuri family. This matters for show preparation: a Kujaku is not judged merely as a Goshiki with shine or as an Ogon with extra markings. Its quality must be read as a metallic patterned koi.

4. Kujaku at a glance: the evaluation hierarchy

The easiest way to avoid being distracted by sparkle is to judge Kujaku in layers. First confirm conformation and health. Next assess the quality and distribution of metallic lustre. Then evaluate the white or platinum ground and the order of the reticulation. Only after that should the red pattern and overall composition decide whether the fish is visually compelling.

The table below summarises the main features.

5. Start with body conformation

Kujaku is a highly decorative variety, which makes it easy to overpay for pattern while overlooking the frame. Use the same conformation discipline that applies to any serious koi. The head should be proportionate and symmetrical, the shoulder should have substance, the body line should flow smoothly toward the tail, and the caudal peduncle should not look weak in relation to the front half.

For a koi expected to grow large, pay particular attention to skeletal balance rather than temporary body volume. A young fish can be lean yet well built, while a heavily fed fish can look impressive without having the frame to carry future size. Pattern and reticulation usually look better on a balanced body because the scale rows have space to express themselves evenly.

6. Hikari: metallic lustre is fundamental, not optional

The defining feature of Hikarimono is metallic shine. In Kujaku, hikari should be present across the head, body and fins rather than concentrated only on a few reflective scales. The head is especially revealing because it has no normal body scales to disguise weak skin quality. A bright, clean head often indicates better overall metallic skin.

Lustre is structural as well as visual. Fish skin contains reflective cells called iridophores, in which guanine-based structures contribute to brightness and reflective colour. Modern carp research continues to show that guanine metabolism and iridophore development are important components of bright or metallic appearance. This does not mean husbandry can manufacture elite hikari from an ordinary genetic base; it means skin quality has a biological foundation that can be supported or damaged by environment and health.

7. How to judge metallic quality correctly

Move the koi or change the viewing angle. Real whole-body hikari remains evident as the angle changes, whereas a single patch of glare can disappear immediately. Compare the head, shoulder, dorsal area, flank and fins. The fish should not look bright only where a lamp is reflecting directly into the camera.

Also separate brightness from whiteness. A platinum-looking ground can still be dull, and a slightly warmer ground can still carry excellent lustre. The best evaluation asks whether the skin is reflective, even and alive rather than simply whether it looks pale.

8. The white or platinum ground

Kujaku is often described as having a metallic white or silver ground. That ground acts as negative space around the red pattern and as the canvas on which the dark scale netting can be read. A clean ground increases contrast; a yellow or dirty ground makes both the reticulation and the red pattern look heavier.

Do not demand the same paper-white shiroji expected from top Kohaku. Metallic skin creates a different optical effect. The goal is a clean, bright and consistent base that supports the metallic character of the variety.

9. Reticulation: the signature net pattern

The dark scale pattern is the feature that gives Kujaku its unmistakable texture. The All Japan Nishikigoi Promotion Association describes a desirable Kujaku as having a distinct mesh pattern of scales. In a refined Wagoi fish, the viewer should be able to follow that mesh in an orderly rhythm along the body.

Good reticulation is not simply ‘more black’. It is disciplined pigment associated with repeated scale structure. When the dark effect becomes random, excessively heavy or different from row to row, the body can look dirty rather than engraved.

10. Reticulation versus Matsuba-type appearance

Kujaku is often discussed using words such as reticulation, netting and matsuba. These terms overlap visually but should not be used carelessly. Matsuba usually describes a pinecone-like dark centre on each scale in varieties such as Gin Matsuba or Aka Matsuba. Kujaku’s official Japanese description emphasises an Asagi-like or net pattern. In real fish, the visual effect can resemble Matsuba because both depend on repeated scale pigmentation.

For buyers, the practical question is simpler: is the scale-by-scale pattern even, deliberate and harmonious with the red markings? A technically argued label does not rescue untidy scale organisation.

11. Scale alignment and why it matters so much

Any koi with strong scale-based patterning exposes irregular scale rows. On Kujaku, a misplaced or regenerated scale can interrupt the dark mesh and become a permanent visual break. Check the shoulder, lateral rows and area behind the dorsal fin carefully, because distortions in these zones are visible from normal viewing angles.

Not every irregularity is genetic. Lost scales can regrow with different pigmentation. That is one reason a seller’s recent history matters when evaluating an expensive koi: what looks like poor reticulation can occasionally be injury-related, while an apparently minor missing scale can later become more obvious.

12. The red or orange pattern

Kujaku typically carries hi ranging from orange to deeper red. The exact hue is less important than consistency, quality and harmony with the metallic ground. A strong pattern should distribute visual weight across the body without covering so much ground that the netting and metallic base disappear.

Imagine removing the reticulation mentally. Does the red pattern still have an attractive shape? Then imagine removing the red. Does the metallic netted body still look refined? A superior Kujaku survives both tests.

13. Beni depth, uniformity and colour food

Deep red is not automatically superior to orange-red. Young koi may carry softer colour, and different bloodlines mature differently. Judge whether the colour is uniform within each plate and whether weak patches, thin edges or inconsistent zones suggest instability.

Diet can influence carotenoid-based pigmentation. Controlled koi studies have shown that carotenoid supplementation can increase colour saturation in red zones. This should be treated as nutritional support, not as a way to create high-grade beni where the genetic and skin quality are absent. Excessive reliance on colour food can also make assessment difficult because the fish may be presented at a temporarily intensified state.

14. Pattern placement on the head

A well-placed head marking gives Kujaku a clear focal point. Pattern that crowds the eyes, mouth or gill plates can make the head look heavy, while a completely blank head can sometimes feel disconnected from a strongly patterned body. Neither condition is an automatic disqualification; balance matters more than a rigid template.

Because the head is also a key area for metallic lustre, look at both pattern and skin together. A beautiful red head marking cannot compensate for a dull or yellowed metallic head.

15. Kiwa and pattern edges

Kiwa is the trailing edge where a red marking finishes against the ground. On a high-quality Kujaku, clean edges help the hi pattern remain readable despite the busy reticulation beneath and around it. Ragged or weak edges can make the pattern look blurred, particularly on a darkly netted fish.

Do not judge a young Kujaku by Kohaku rules alone. Metallic skin, reticulation and age can change the apparent sharpness of boundaries. The question is whether the edge structure is appropriate for the fish’s age and whether the pattern is consolidating rather than deteriorating.

16. Sashi on young Kujaku

Sashi is the leading-edge appearance of pigment where the next scale row overlays developing colour. It can be visible in young patterned koi, although metallic skin and reticulation may make it harder to read than on Kohaku. A small amount of orderly sashi may be compatible with normal development; broad, irregular or inconsistent leading edges deserve closer inspection.

When buying from photographs, do not overinterpret sashi from a single image. Reflections and dark scale centres can create false edges. Video and multiple stills are much more useful.

17. Fins and the importance of clean metallic pectorals

The pectoral fins should look balanced, intact and bright. Metallic quality in the fins reinforces the whole-body impression of hikari. Dull, opaque or damaged pectorals can reduce refinement even when the body is attractive.

Look for symmetry in fin size and ray structure. Small red or dark markings in the fins may or may not be aesthetically acceptable depending on placement, but heavy staining can make the fish look untidy.

18. Tail stop and the rear third

The rear third is often neglected when buyers focus on the head and shoulder. A useful Kujaku pattern normally leaves enough visual separation near the tail to avoid a crowded finish. The tail tube itself should retain enough body strength to support future growth.

The reticulation should also remain organised toward the peduncle. A fish that is beautifully netted at the shoulder but becomes chaotic at the rear may look less refined as it grows and the back half becomes more visible.

19. Pattern balance: how much red is enough?

There is no universal percentage of red that defines a good Kujaku. Some excellent fish are relatively light, allowing the silver netted ground to dominate; others carry broad red plates that create a more powerful impression. Balance depends on body shape, contrast and distribution.

A useful test is to divide the fish mentally into head, front body, middle and rear. If one zone contains nearly all the red while the others are visually empty, the composition can feel unstable. Strategic negative space is desirable; accidental emptiness is different.

20. The relationship between hikari, netting and hi

Kujaku quality is multiplicative rather than additive. Excellent red over poor metallic skin still looks ordinary. Strong hikari with random reticulation can look flashy but crude. Perfect netting on a weak body will not become a top-class koi.

This is why mature high-quality Kujaku can be difficult to produce. Several independent-looking traits must remain compatible as the fish grows and its scale pattern expands.

21. How Kujaku changes with age

Young Kujaku may have light reticulation, softer red and a less imposing metallic surface. As the fish matures, the scale pattern can become more obvious and the body can gain the width needed to display it. Darkening is not automatically improvement: if the reticulation becomes coarse or overly heavy, the fish may lose elegance.

The red can also change in apparent depth as the skin thickens and body size increases. Evaluate development as a trajectory, not a promise. Photos of siblings, older koi from the same pairing and the breeder’s track record can provide context, but no responsible assessment can guarantee exactly how one individual will finish.

22. Tosai: what to prioritise

For tosai, conformation, skin quality and scale order usually deserve more weight than a finished-looking pattern. Look for a straight body, clean head, balanced frame for age and reticulation that appears regular rather than randomly dark. The hi should be reasonably even, but it may still be youthful in tone.

Avoid choosing only the darkest or reddest baby koi. An unusually finished tosai can be attractive, but future quality depends on whether the body and skin have room to mature.

23. Nisai: when the structure becomes easier to read

At nisai, the relationship between body, scale rows and pattern is clearer. This is a useful stage for evaluating whether the netting is becoming organised across a larger frame and whether metallic quality is holding across the head, shoulders and flanks.

Nisai also reveals more about sex characteristics, growth trajectory and colour stability, although certainty is still limited. For buyers paying a premium, this stage often provides a better balance between developmental information and remaining upside than very young tosai.

24. Sansai and older Kujaku

Older fish allow a more direct assessment of what is actually present. Body conformation, lustre, reticulation and hi quality can be judged with fewer assumptions. At the same time, defects are harder to dismiss as temporary development.

On a mature Kujaku, the highest praise is usually coherence. The koi should not look like a collection of separate effects. Its metallic skin, scale netting and red pattern should reinforce one another across a strong body.

25. Male versus female Kujaku

Female koi often have greater potential for body volume and large-frame presence, while males can maintain intense colour and may mature earlier visually. These are tendencies, not rules. A high-quality male with excellent conformation can be more desirable than a mediocre female, especially for smaller size classes or a private collection.

Do not buy sex instead of quality. The correct question is whether the individual’s body, skin and pattern fit your objective—growth, showing, breeding interest or visual enjoyment.

26. Doitsu Kujaku

The All Japan Nishikigoi Promotion Association recognises Doitsu Kujaku, in which most ordinary body scales are absent and the skin is exposed while the fish retains Kujaku characteristics. The visual experience is different because the repeated Wagoi scale mesh is reduced or reorganised around the remaining dorsal and lateral scales.

On Doitsu Kujaku, scale placement becomes extremely important. A neat dorsal row can create powerful structure, while irregular oversized scales can dominate the design. Judge the skin itself for metallic quality and cleanliness because there are fewer normal scales to carry the visual effect.

27. Ginrin Kujaku

Ginrin Kujaku adds highly reflective Ginrin scales to an already metallic fish. This can produce exceptional brilliance, but it can also become visually busy. The underlying Kujaku must still have good conformation, organised pattern and quality reticulation.

Do not use sparkle to excuse disorder. In a refined Ginrin Kujaku, the additional reflective scales should enhance the design rather than hide uneven pigment or poor scale rows.

28. Tancho Kujaku

The All Japan Nishikigoi Promotion Association lists Tancho Kujaku and Doitsu Tancho Kujaku. The essential visual idea is a round scarlet head marking combined with the other defining characteristics of Kujaku. This creates a particularly demanding balance because the body pattern is restrained while the netting and metallic ground become more exposed.

The head marking should be judged for placement, shape and colour quality, but the koi still needs excellent body and hikari. A nearly perfect circle on a weak fish is not enough.

29. Kujaku versus Gin Matsuba

Gin Matsuba is essentially a metallic white/silver koi with dark scale centres that produce a pinecone or netted effect, but without the Kohaku-like red pattern of Kujaku. This makes Gin Matsuba an important comparison because a red-poor Kujaku can superficially resemble it.

The distinction is straightforward when the Kujaku has clear red plates. The deeper lesson is that Kujaku borrows visual power from the same disciplined scale patterning that makes high-quality Matsuba varieties attractive.

30. Kujaku versus Goshiki

Both varieties can combine red markings with dark reticulation, so photographs sometimes create confusion. The critical difference is metallic character. Kujaku is a Hikari variety with whole-body lustre; Goshiki is non-metallic and is judged around its complex ground colour and Asagi-derived reticulation.

A second difference is visual temperature. Goshiki often reads as smoky, grey, blue or black beneath bright red, while Kujaku should read as reflective silver/platinum with a metallic finish. If the fish does not shine across the whole body, calling it Kujaku should be questioned.

31. Kujaku versus Hariwake

Hariwake is another Hikari-moyo family member, normally showing metallic white with yellow, orange or gold patterning. What it lacks is the defining dark scale netting of Kujaku. A clean Hariwake can therefore look simpler and more open, while Kujaku is structurally busier because the scale pattern is part of the design.

When a Kujaku has weak reticulation, it may approach a Hariwake-like appearance. Whether that is attractive is subjective, but a fish sold as high-quality Kujaku should still express its characteristic scale pattern clearly enough to be identifiable.

32. Kujaku versus Sakura Ogon / metallic Kohaku

Sakura Ogon, also described in Japan as Platinum Kohaku, presents a metallic Kohaku-like red-and-white pattern without Kujaku’s defining reticulation. This comparison is useful because it isolates the role of netting: if the dark scale pattern vanished from a Kujaku, the remaining red-over-metallic-white layout might resemble Sakura Ogon.

For selection, this means the reticulation is not decoration added at the end. It is one of the core identity traits of Kujaku.

33. Current show classification

Zen Nippon Airinkai places Hikari-moyomono in Group 2. The class covers metallic-bodied koi with two or more colours, excluding the Utsuri family. Kujaku therefore competes within a broader class that can contain other metallic patterned varieties rather than in a dedicated Kujaku-only division.

Exact classes and size divisions vary among show organisations, so exhibitors should always check the current show schedule and entry rules. The practical consequence is that a strong Kujaku must demonstrate excellent general Hikari quality as well as variety-specific netting and pattern.

34. How a judge is likely to read Kujaku

Formal judging systems differ, but the fundamental hierarchy remains familiar: conformation and overall quality first, then skin, lustre, colour, pattern and the refinement appropriate to the variety. On Kujaku, poor hikari is especially damaging because metallic skin is foundational rather than optional.

A show fish should also be presented in excellent condition. Damaged scales, fin tears, stress colour and poor skin can undermine traits that might otherwise be competitive.

35. A practical evaluation sequence

When examining a Kujaku in person or on video, use a repeatable order so that sparkle does not control the decision. Start with body and swimming. Check head and whole-body hikari. Read the scale rows and reticulation. Evaluate the ground. Assess the red pattern and its edges. Inspect fins and the tail area. Only then decide whether the entire fish feels balanced and refined.

This sequence is especially useful at auctions, where excitement and time pressure encourage buyers to jump directly to pattern.

36. Common faults and weaknesses

Common weaknesses include dull metallic skin, especially on the head; uneven or broken reticulation; excessively dark, dirty-looking scale pigment; weak red; yellowed ground; damaged or misaligned scales; poor conformation; and patterns that become crowded because too little metallic ground remains visible.

The most important distinction is between a fault and a style preference. A light reticulation style may still be excellent if it is even and intentional. A red-heavy pattern may still be balanced on the right body. Randomness, inconsistency and weak skin quality are more serious than simply being different from your preferred look.

37. Evaluating Kujaku from photos and auction videos

Metallic koi are among the easiest fish to misread online. Bright lights can create artificial sparkle, oversaturated cameras can deepen orange-red to crimson, and blue bowls can increase the perceived cleanliness of silver skin. Ask for moving video whenever possible and watch the fish as it turns away from the main light source.

Pause the video at the shoulder, mid-body and tail. Check whether the reticulation remains orderly across different angles. Compare the head with the body for lustre. Look at the pectorals for brightness. If the fish looks brilliant in only one still image, discount the presentation and focus on structural information.

38. Buying from a breeder or dealer: questions worth asking

For higher-value Kujaku, useful questions include age, measured size, sex or sex estimate, breeder, parent set if known, history of lost scales, recent treatment, feeding regime and whether the photos were taken immediately after colour food. None of these answers guarantees future quality, but they improve context.

Older photos can be particularly valuable. A sequence showing the same koi six or twelve months earlier tells you more about developmental direction than a seller’s adjective such as ‘future show quality’.

39. Malaysia and other warm climates

Kujaku can be kept successfully in Malaysia, but year-round warm water changes the husbandry context compared with temperate Japan. Warm water holds less dissolved oxygen, koi metabolism stays relatively active, and heavy feeding can increase biological load. These factors matter because skin quality and lustre are best preserved in a stable, low-stress environment.

Avoid assuming that warmer water will automatically improve or ruin colour. Controlled koi studies show that temperature fluctuations can alter skin brightness and pigment-related metabolites, but responses differ by colour type and experimental conditions. The practical target is stability: high oxygen, low ammonia and nitrite, controlled nitrate and organic load, and enough filtration capacity for the stocking density.

40. Water quality and metallic skin

Clear water is not the same as high-quality water. For metallic koi, accumulated dissolved organics and chronic gill stress can make a collection look flat long before an obvious health crisis appears. Maintain adequate turnover, mechanical removal of solids, mature biofiltration and regular water replacement appropriate to your source water.

Stable pH and alkalinity are also important because repeated pH swings create physiological stress. Rather than chasing a special ‘Kujaku parameter’, maintain a safe, stable environment suitable for healthy koi and compare changes in skin quality over months rather than days.

41. Temperature, oxygen and stress

In a hot pond, aeration should be treated as core life-support rather than an accessory. Waterfalls, showers, diffusers and strong circulation can help, but actual dissolved oxygen depends on temperature, biomass, feeding and system design. Night-time oxygen demand can be significant in heavily stocked ponds.

Research on koi has shown measurable skin-colour responses to acute temperature fluctuations. This supports a conservative husbandry principle: avoid unnecessary thermal swings and transport stress when trying to condition a metallic show koi. It does not support trying to manipulate temperature aggressively to force a desired colour.

42. Feeding for colour without sacrificing the fish

A complete diet with appropriate protein, lipid, vitamins and minerals comes before colour enhancement. Carotenoids can affect red and orange pigmentation, and multiple koi studies have demonstrated measurable changes from carotenoid-containing diets. However, more pigment is not automatically better. Growth, digestion, water quality and the natural hue of the variety must stay in balance.

For a Kujaku, the goal is not simply the deepest red possible. You also want clean metallic ground and strong lustre. If heavy feeding or excessive colour food damages water quality, the trade-off can be counterproductive.

43. Sunlight, algae and viewing conditions

Natural light can make metallic skin look exceptional, but uncontrolled exposure is not a substitute for husbandry. Outdoor ponds should provide conditions that protect koi from overheating and allow them to move away from intense sun. Shade also helps reduce rapid temperature swings and can make observation easier.

Green water, algae and tinted pond water change how Kujaku appears to the eye. Always evaluate expensive koi in a clean inspection bowl under neutral lighting before making conclusions about ground colour or hikari.

44. Handling, transport and scale damage

Kujaku’s scale-based pattern means physical damage can have an outsized cosmetic effect. Use adequately sized nets and socks, avoid rough handling, and make sure transport bags do not allow the fish to strike hard surfaces. A single lost scale in a central reticulated row may remain visible even after healing if pigmentation regrows differently.

After import or long transport, evaluate condition before cosmetics. Temporary dullness can reflect stress, mucus changes or recovery. Give the koi appropriate quarantine and stable water rather than immediately trying to ‘fix’ colour through feeding.

45. Common myths about Kujaku

Myth: the darkest reticulation always means the best Kujaku. In reality, refinement and consistency matter more than maximum darkness. Myth: bright lighting proves strong hikari. Real metallic quality should remain visible across angles and lighting conditions. Myth: colour food can create top-grade red. Nutrition can influence saturation, but it cannot replace genetics, skin structure and health.

Another common myth is that every young Kujaku will become more attractive as the netting darkens. Development can improve definition, but it can also make an already heavy fish look coarse. Buy the quality that is present and treat future improvement as upside rather than certainty.

46. Frequently asked questions

Is Kujaku a metallic Goshiki? No. They can look related because both may show red over dark reticulation, but Kujaku is defined by whole-body metallic lustre and is classified with Hikari-moyomono; Goshiki is non-metallic.

Should Kujaku have black on every scale? Not necessarily in the crude sense of identical black centres. The desired effect is orderly, recognisable netting appropriate to the fish’s style. Excessive or random darkness can reduce refinement.

Is orange hi inferior to deep red? Not automatically. Uniformity, skin quality, balance and developmental stage matter. Some young fish mature in colour, and individual lines differ.

Can Kujaku be Doitsu? Yes. The All Japan Nishikigoi Promotion Association recognises Doitsu Kujaku. It has exposed skin with limited scale rows while retaining Kujaku characteristics.

Can Kujaku be Tancho or Ginrin? Yes. Japanese variety references list Tancho Kujaku, Doitsu Tancho Kujaku and Ginrin Kujaku forms.

What matters most when buying tosai? Start with body, health, metallic skin and orderly scale structure. Do not let intense red or a flashy photograph override those foundations.

47. Buyer’s checklist

Before purchasing, work through the following checklist rather than asking whether the fish simply looks impressive.

• Body is straight, balanced and appropriate for the intended growth goal.
• Head is clean and carries convincing metallic lustre.
• Hikari remains visible across body and fins from more than one viewing angle.
• Ground is clean and does not look yellow, muddy or patchy.
• Reticulation is orderly, consistent and compatible with the scale rows.
• Red/orange markings are even enough for the koi’s age and distributed attractively.
• Scale rows are not interrupted by obvious injury, missing scales or irregular regrowth.
• Pectoral fins are balanced, intact and bright.
• The rear third and tail tube remain strong rather than visually collapsing.
• Photos and video agree; the fish is not attractive only in one highly lit still image.
• Age, size, breeder, sex estimate and recent treatment history are known when the price justifies asking.
• Future development is being treated as uncertain upside, not as a guaranteed sales claim.

48. Final perspective

Kujaku is at its best when complexity remains controlled. Metallic lustre gives the fish energy, the scale netting gives it texture, and the red pattern gives it composition. If any one component overwhelms the others, the koi can become flashy without being refined. The strongest fish keep all three in balance on a body capable of carrying the design as it grows.

For serious selection, remember the order: body first, then skin and hikari, then scale organisation, then colour and pattern. That discipline is especially valuable with metallic koi because brilliance can create an immediate emotional response. A Kujaku worth keeping for years should still look impressive after the glare is mentally removed.