Choosing Young Koi With Potential (Part 1 of 2)

For the purpose of the upcoming Seijuro Grow-Out Event, I have been revisiting some of the materials that I came across some months or years back on the topic of selecting tosai (1 year old and under) with potential.  Koi enthusiasts, both new and old, will never ever get bored of this discussion. I applied some of these principles when I picked the Showa tosai I discussed in “A Tateshita Koi with Jumbo Potential – Dream or Reality?“, while it’s too early to be conclusive but it’s all going in the right directions so far.

While it is easy to spot a koi with good body when it is a nisai (2 years old) and above, it is always not the case for tosai especially when they have to be quarantined for several weeks in Japan before shipping and several weeks more after arriving at the dealer’s facility.

So what should we look for in a tosai?

Head

A good head will be broad and long, with a wide mouth, and the eyes set a good distance apart and not close to the mouth. It is quite common to see koi that have a narrow or short head, with the eyes being too close to the mouth. Such koi will seldom get big and should be avoided. Another aspect to look for is that the gill covers follow the same smooth line as the overall head shape, and do not flare outwards just before the body.

Body Height (Jitai)

Jitai means ‘height’ and quite literally refers to the height of the body of the fish. A hump behind the head is not Jitai and it is little bearing on size in the future although its presence will make the fish look ‘bulkier’. Jitai is the height of the body of the koi between the back of the head and the highest point of the body. A good strong curve up over the back of the koi is a good attribute and a key factor in determining size potential, as well as helping determine the kind of body shape the koi will develop. Also, when looking at Jitai, you will often see that it is prominent in such a way that it looks as if the koi will be able put on more weight in the shoulder area. This can help you understand the way the shape will develop. One thing that you should remember is that good Jitai is important, but it is still possible to have a koi that has too much height, which will make the fish look short in relation to its build.

Height of Body (Jitai)

Tail section (Ozutsu)

Ozutsu refers to the part of the body located from the end of the dorsal fin to the root of the tail, which is also called the tail joint. It is an important section because it contains the Odome. In addition, Nishikigoi with thick Ozutsu look powerful, while koi with thin Ozutsu look feeble. If a Koi has a thick Ozutsu while it is young it may have the potential to grow into a Jumbo Koi.

Tail section (Ozutsu)

However, in very small koi the tail joint will tend to blend subtly in to the tail, making it somewhat harder to assess. Another factor that needs to be watched is the depth of the tail joint, as a shallow tail joint can often make a female koi look overly female as it grows, and will also make the tail pipe look too thin. Carefully choosing a koi that has good Ozutsu can help you obtain a koi that will keep a good, strong but trim body as it approaches jumbo size.

Next week, in Part 2 of this article I will be discussing patterns in young koi and sumi quality.