The Heart of Koi Appreciation
While every part of the koi hobby is interesting, the real joy comes from learning to appreciate koi for what they are. If koi weren’t so unique, beautiful, and capable of changing as they grow, much of the interest in the hobby would be lost.
We have shared some helpful videos from Koi USA Seminars that show how koi can change over time. In this guide, we also include tips for buying koi and avoiding common beginner mistakes.
Common Mistakes Beginners Make
One mistake we often see is when people compare a mature, prize-winning koi to a small, inexpensive six-inch fish. They expect the same look without understanding that koi change as they grow. Their colors can become stronger and more defined, sometimes in a very noticeable way.
Also, raising a low-quality fish takes the same time and pond space as raising a good one. It’s usually better to buy one high quality koi fish than two or three that are not as promising.
Understanding Koi Head Structure
These two koi are both Sandan Kohaku in the 12–14 inch range and were brought in during 2009. When you look at the body, color, and pattern, you can see a clear difference in the head shapes.
The koi on the left has a more balanced and attractive head shape, which is correctly proportioned. The one on the right has a pointed head with very little width or depth behind the eyes. This lowers its value compared to the first fish. The pattern on the head, known as the head plate, is also much better on the first koi.
For proper balance, the width at the back of the gill plate should match the length from the nose to that same point.
Tips for Buying Koi
To choose young koi with good potential, it helps to know how they develop. Here are some basic points to consider. The main rule is: quality is more important than quantity.
Do You Actually Like the Fish?
This is the most important question. Don’t worry about whether the fish will win shows. Ask yourself—do you truly like it and want it in your pond? You should be excited about adding it to your collection.
Body Shape (Also Known as Conformation)
Does the fish have a strong, balanced shape? A good koi should look powerful and well-formed from head to tail, including the fins. Female koi often have fuller bodies, which makes them more expensive. More details on body shape are below.
Color Balance
Sometimes a koi will have a great-looking pattern when it’s small, around 8 inches. But take a young sanke, for example—if it has no red (beni) behind the dorsal fin, what looks nice now could appear unbalanced when the fish grows to 18 inches.
White Areas (Shiroji)
The white color on koi doesn’t always improve as the fish grows. However, some exceptions exist—certain types like shiro utsuri and showa can have much better white areas as they age. Also, fish from some breeders are known for improving over time. On small kohaku, the white should be even and clean. Pay special attention to the white on the head and compare it with the rest of the body.
Black Areas (Sumi)
If a young koi has very dark black areas, it’s not always a good thing. That black can take over the fish or even fade later. Instead, look for black that is just starting to appear—it’s often a better sign. Some visible inky black is good. Remember, black patterns grow over time, and the way they develop depends on the koi’s type and bloodline (for example, showa versus sanke).
Red Areas (Beni or Hi)
Many people want bold red colors on small koi, but it’s actually better to look for soft orange without clear patches or holes (called “windows”). A diamond-shaped red in the middle of the scales is a good sign that the color will deepen and last longer.
Fish under 10 inches that already have dark red may be male and may lose their color sooner. Also, red areas shrink as the koi grows. So, a red spot that looks balanced at 10 inches may not look right at 20 inches.
In some cases, a full tancho spot (a red mark on the head) can even disappear over time. Take a look at the San Jose clip on the AKCA Seminar page—there, a tancho sanke becomes a beautiful bekko.
Small Differences, Big Price Changes
Even top-quality koi have flaws. A koi that wins a show is likely at its peak. While two fish may look similar, a 10% difference in quality can lead to a much higher price—sometimes double.
Things like deep, soft red (beni), shiny skin, and perfect shape are rare and don’t come cheap. When buying koi, much of the cost depends on the fish’s potential.
Be Careful with Koi Photos
Photos can help you judge a koi’s quality, but they don’t tell the whole story. You can’t see how the fish moves or how shiny its skin is. You also miss the side view, which shows important features like black wrapping (sumi), the color near the tail (peduncle), and the body shape.
Also, photos may not show the true color or thickness of the red areas. Because of this, you should not spend a lot of money on a koi just by looking at a photo.
Looking at Body Shape
Many beginners make the mistake of judging koi by their colors and patterns first. But the body shape—called conformation—should come first.
Think of it like judging people: a good koi should look strong and well-proportioned, like an athlete, not skinny or weak. Look for broad shoulders and a thick tail area, with no dips or pinches. Check the abdomen—if it has a pinch at the back, that won’t go away.
A good koi will have a head and fins that are in proportion to its body. Strong bone structure and a good distance between the dorsal and tail fins are signs the fish could grow to a large size.
It’s not easy to describe, but once you see a high-quality koi in person, you’ll understand what a strong body adds to a fish’s overall appearance. After that, skinny koi just don’t look right.
Understanding koi body shape, skin quality, shine, and movement takes time. If possible, try to see top-quality koi up close and compare many of them. This is the best way to improve your ability to judge koi.
Things to Think About When Buying
Bigger koi cost more because fewer can fit in a shipping box, and they’ve already passed through several rounds of selection in Japan. This means they are worth more.
Also, you can’t raise big, beautiful koi in a small 12-foot pond with no bottom drain and cheap food. Koi need clean water, good food, deep ponds, strong water flow, good air supply, and a long growing season—at least 8 months—to reach their full potential.
Know What You’re Looking For
When you’re picking a fish, ask yourself a few questions:
- Which one looks best now?
- Which one has the most potential in the future?
- Which one do I like the most?
- Do I want a male or female?
- How old should the fish be?
You may end up with three different fish for each answer. In the end, having knowledge and understanding of what you’re seeing is what will help you choose the best koi for your pond.
