One of the main successes with ranchu, as a breeder, lies in training yourself to be able to identify and recognize merits of this fine goldfish variety. This very ability of the breeder ensures that ranchu standards will be preserved and further improved. Being under scrutiny for over one hundred years, ranchu were "molded" to fit into strict standards set by high Japanese aesthetics. Therefor, Japan Ranchu Association (JRA) has established a series of rules, by which the ranchu to be judged. These rules are vague and has to be interpreted by a group of most experienced judges on the show.
I found these rules posted by Hugoboss on Arofanatics website in 2008. According to the post these are the rules of Japan Ranchu Association that have been translated to English. With further improvement in translation, I am re-posting these rules here. For identifying ranchu body part click on "Defining What Is What".
ARTICLE 1 - Particular Matters of Concern
1. Overall fish shape and balance
Overall shape is defined by the characteristics of the head, torso and tail and their balance with each other and as a whole.
2. Fish to be thick and sturdy
Thicker and sturdier fish in proportion to its size to be graded as superior.
3. Scaling and color
Scales that are neatly lined and small in proportion to the body of the fish to be graded as superior. Fish with deep red or gold colours and high luster to be graded as superior, regardless of being aka (red), sarasa (mottled) or shiro (white).
4. The fish movement must be as graceful as possible
5. Fish maintaining noble grace to be regarded as superior
6. Swimming
Swimming fish must be elegant, with light wagging of tail resulting in fluid movement.
ARTICLE 2 - The way to view fish body parts
1. Head
To have wide mehaba (spacing between the eyes) and wide mesaki (distance between the eyes and the mouth). Part of the head past the mouth, which is adequately wider and longer to be graded as superior (with variety of Tokane, Kamicho, Ryuutou etc.).
2. Back
2. Back
To have a broad back with a gentle curve and adequate roundness.
3. Stomach
To be well-positioned compared to the back and spaced adequately from the tail.
4. Tail Peduncle
4. Tail Peduncle
To chose the fish with more rounded and robust tail peduncle in proportion to the back width. There must be apparent roundness at the point where the tail joints the back.
5. Tail
Tail must be beautiful with bilateral symmetry of its tail lobes and with adequate ozara (under tail plate). This equally applies to yotsuo, sakurao, mitsuo tail types. The tail must neither exceed approximately 90 degrees angle in relation to the tail peduncle, nor rise above the back.
6. Fins
6. Fins
All fins must be uniform in movement and size. Fish to be judged equally regardless whether they have double or a single anal fin.
ARTICLE 3 - Size of fish must not be taken into consideration for judging
ARTICLE 3 - Size of fish must not be taken into consideration for judging
ARTICLE 4 - Fish must be judged according to their quality on that particular day
Supplementary provisions. Names of color patterns are designated as follows.
1. Red section - Kiniro, Niiro, Shoujou
2. White section - Shiro, Giniro
3. Sarasa section - Taseki Sarasa, Tashiro Sarasa, Koshijiro, Seaka, Shirohara
4. Head pattern - Omoyaburi, Omoshiro, Omosarasa, Tanchou, Ryoudo, Kuchibeni, Mado, Ougashira
ARTICLE 5 - Fish to be disqualified if the respective defects are excessive
1. No judging of fish with dorsal fin, double tail or other deformities.
2. White section - Shiro, Giniro
3. Sarasa section - Taseki Sarasa, Tashiro Sarasa, Koshijiro, Seaka, Shirohara
4. Head pattern - Omoyaburi, Omoshiro, Omosarasa, Tanchou, Ryoudo, Kuchibeni, Mado, Ougashira
ARTICLE 5 - Fish to be disqualified if the respective defects are excessive
1. No judging of fish with dorsal fin, double tail or other deformities.
2. Uneven or broken back curve or tail peduncle.
3. Pinched, closed, irregular, curled or stripped tail.
4. Extrusion of anal fin(s); head tilted upwards; head tilted downward; tail with one-sided tilt; covered, protruding or indented eyes.
5. Sick fish
ARTICLE 6
Obese or juvenile fish that lacks of grace and poise shall be disqualified
ARTICLE 7
Prizes will be revoked in case of falsifying the age of exhibited fish
Here are some videos of the champion ranchu in each age group (tosai, nisai and oya) taken by Mr.Boss (Boss Ranchu Nursery, Thailand) during All Japan Ranchu Show, 2013.
TOSAI
NISAI
OYA