After spawning, a female eats food very aggressively and gets ready for the next season. Males do not have as big of an appetite as the females. Typically, the female eats more and ends up growing bigger in girth and length.
It is one of the clues. Breeders can estimate the age simply by looking at the koi. Breeders can tell the age by collecting various information such as body conormation, coloration, head and fins size, scale size, thickness of fukurin, etc.
Goshiki is bred by crossing Asagi with Kohaku. Aigoromo came from the process of leaving pattern only on the Hi, making the other part white. Simply speaking, Aigoromo has white as its ground and Goshiki has color there, and sometimes Hi as well.
They come from the same parents. Bekko is a koi with Sumi (xsimu) on the shiroji that is bred from Taisho Sanshoku. Sometimes koi with sumi on red skin appears. This is Hi Bekko. Hi Bekko and Bekko are brothers and sisters of Taisho Sanshoku.
The season depends on the location. The temperature of the water triggers the spawn. In hot places like Okinawa, the season begins in March, while in Niigata it is in May and June. In tropical countries, it is possible for the Koi to spawn 2-3 times per year.