Koi Judging Criteria Show Prep Guide: ZNA and Beauty Standards
Walk a koi show table at the Singapore Koi Club annual and you will hear judges debate margins of millimetres on kiwa edges and degrees of luster on hi plates. The koi judging criteria developed by Zen Nippon Airinkai (ZNA) and All Japan Nishikigoi Promotion Association (Shinkokai) standardised the way these decisions are made, and serious show keepers train themselves to think in those exact terms. This guide from Gensou Aquascaping at 5 Everton Park covers the four-pillar ZNA scoring system, what wins each category, and how to prep a koi for show day.
The ZNA Four-Pillar System
ZNA standards weight four areas equally at 25 per cent each: body conformation, skin quality, pattern, and deportment. A perfect 100-point fish does not exist — top show winners typically score 88-94. The pillar weighting protects against pattern-only judging and rewards koi that perform across all four metrics. Shinkokai weighting differs slightly but follows the same pillar logic.
Body Conformation (25 Per Cent)
Judges assess body line from above and from the side. Strong shoulders, balanced volume mid-body, smooth taper to the caudal peduncle, symmetric finnage, and an even spine all score. Penalty marks for pinched shoulders, hollow bellies, asymmetric caudals, missing scales, scoliosis, or cropped fins. Female koi typically score higher because they reach jumbo more easily and hold rounded body lines. Body cannot be improved through preparation — it is fixed at the time of selection.
Skin Quality (25 Per Cent)
Skin scoring covers shiroji whiteness, hi tone depth, sumi blackness, scale uniformity, and the underlying luster (called fukurin in some standards). Show-grade hi reads vibrant orange-red, not patchy lipstick gloss. Sumi reads deep ink-black, not grey or brownish. Shiroji reads milky-clean, not cream or yellow. Skin quality responds to water hardness, feeding, and pre-show conditioning over months.
Pattern Balance (25 Per Cent)
Pattern criteria differ by variety but follow consistent themes: balance across the body, clean kiwa (hi-shiroji edges), strong head pattern, and stable sashi (advancing hi edges). Kohaku judges look for 3-5 well-spaced hi plates with no single dominating plate. Sanke and Showa judges weight sumi placement equally with hi. Goshiki and kujaku judges assess matsuba pattern uniformity. Variety-specific judging guides cover each pattern type in detail.
Deportment (25 Per Cent)
Deportment is how the fish presents itself in the show vat. Confident swimming, balanced posture, alert but not frantic behaviour, and no obvious signs of stress all contribute. Penalty marks for clamped fins, listing posture, surface gulping, or hiding in the corners. Pre-show conditioning to acclimate the koi to confined-vat environments matters here. The fish must feel comfortable in the show tub.
Pre-Show Conditioning Schedule
Twelve weeks out: switch broodstock-quality colour-enhancement feed (Saki-Hikari Colour Enhancing) at 2 days per week. Six weeks out: heavy water exchanges (10-15 per cent daily) to deepen skin tone. Four weeks out: salt bath at 0.3 per cent to remove parasites and brighten skin. Two weeks out: switch to vat acclimation in a show-style tub of similar volume. One week out: fasting protocol — last full feed 5-7 days before show. Stock from the water care and treatment shelf and the fish food and feeding range support the conditioning chain.
Show Day Logistics
Transport in oxygenated bags inside insulated boxes; aim for 22-25°C transport temperature. Singapore Koi Club shows typically run two days. The fish enter shallow (40-50 cm) viewing vats with strong aeration and gentle filtration. Vats are arranged by size class: tosai (under 20 cm), nisai (20-40 cm), sansai (40-55 cm), yonsai+ (55-70 cm), jumbo (70 cm+). Within each size class, fish compete by variety category.
Singapore Shows and ZNA Affiliation
The Singapore Koi Club runs an annual show under ZNA-affiliated rules. Entry fees run SGD 30-100 per fish per category. Top awards include Grand Champion (best in show, weighted toward jumbo), Adult Champion, Young Champion, and best-in-variety titles. Equipment for show prep — tubs, transport gear, water testing kits — comes from the aquarium equipment range. Build relationships with judges and senior keepers; the network drives access to top tategoi.
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