Another reference,

About one famous young breeder in Japan.

He breed his ranchu and raise them in a 6' x 6' pond. Along the way, from the same pond and from hundreds and thousands of fries, he cull the babies off according to their growth. From 100,000s to 50,000 to 10,000 to 5000 to 1000 to 500 to 200 to 100 to 50 to 40 to 30 to 20....... so on. Eventually, he has about 10-15 fish in each pond. He pick the best of each pond and grooming will be according to what the best fish required as reference for each and every pond. the rest will be the "king of the pond's" companion. Lastly, he'll pick the best out from each pond and choose the best of the best for competition.

Target:
Only ONE fish out of a million.

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Japanese Ranchu is another ball game