From Isa koi farm, "We think there is no effective way to breed Nishikigoi. I said this because a female Nishikigoi spawns 300,000 to 1,000,000 eggs during spawning season. However only about 100 to a 1,000 Nishikigoi eggs will get through the culling process. Likewise, if a Nishikigoi breeder can produce one ideal Nishikigoi in his life, he is lucky."