Many people have asked me to help choose fish for them that I think will become a show winner. For this reason, I am writing some articles on what I think people should look for in small koi if they plan on showing them someday. I wanted to write about the kohaku first, because I believe that is the most important fish if you are looking for a future grand champion and it is the basis for other varieties. When looking at a large number of kohakus, perhaps hundreds at a time, the first thing I look for is a white tip at the front and back of the fish. It is preferable to have the red on the head of a kohaku to only go down about as far as the nostrils. Also, the head must have red on it. Don't pick a kohaku with an all white head. Red over the eyes of the koi used to be looked down upon, but in modern times it may come down over the eye. However, I think it is better if the red only comes down over one eye, not both eyes at the same time.
The head is generally one of the most important parts in an early koi. Now that you have several koi with acceptable head patterns, I look at the rest of the body. As I said earlier, I also look to see if there is a white patch right before the tail. If at all possible, I would like one there, but if all the rest of the koi has positive characteristics, this is not as important as the head.
For the body, I look for red that is balanced side to side and covers 70% of the body. This is so that as the koi grows up, and the white comes up, there is still adequate red on the body. The red on the body can be in a zig_zag pattern (inazuma), a three or four step pattern, or anything else that looks eye catching. If the red is straight with no signs of breaking, the pattern may be uninteresting as the koi grows. I also look for koi that are broad at the shoulders, have a large skull, and have relatively large pectoral fins. This generally means the koi will grow larger to compete in shows.
When buying young kohakus, don't worry too much about the color. The white should preferably be snow white but may also be pink if it was color fed before shipping. Avoid kohakus with a dirty grayish_white. As for the red, it may be either bright red or orange_red. Many orange_red young kohakus turn a pretty red as they grow. Next make sure there are no red or black marks on any of the fins. A small red patch at the base of the pectorals may be okay. Also, make sure there are no black marks on the body. All red on the body should also be in sizeable patches, not in single scale areas (ie. small red spots).
Last, but not least, take the koi out in a show tub and check for any body defects or any signs of disease. If these exist, do not buy the fish no matter how nice it looks. I hope this information can give you some help in selecting kohakus. Who knows? In 7 years you may have a grand champion.