A Kohaku is a koi with a white base and red markings. That simple color combination makes it easier to recognize than many multicolored varieties, but no two fish need to have the same pattern. Start with what you can see clearly, then enjoy the details that make an individual koi distinctive.
Start with the two colors
Look for a white body carrying areas of red. The red marking is often called hi. Its shape may be broad, broken into separate patches, or arranged in a line along the back. A fish with prominent black markings calls for a closer look at another variety rather than being identified as a straightforward Kohaku.
Good light helps. Observe the fish from above and from the side as it swims instead of trying to decide from a single photograph or a split-second glimpse.
Notice how the red is arranged
Some Kohaku have one continuous area of red; others have several separate areas, often described as steps. A two-step pattern is commonly called nidan, and a three-step pattern sandan. Counting steps describes the layout, not the fish's health or how enjoyable it will be in your pond.
You may also encounter a Kohaku with a single red spot on the head, often called a Tancho Kohaku. As with any pattern name, use it to describe what you see rather than assuming a fish's future appearance is guaranteed.
What do koi enthusiasts look at?
People interested in show patterns may pay attention to the clarity of the white, the richness and placement of the red, the transition between colors, and the fish's overall body shape. A white area near the tail and fins that remain white are common preferences in traditional descriptions. These are preferences for a particular look, not requirements for a koi to be beautiful or suitable for a home pond.
Color can change as a koi matures, so an orange-red young fish should not be promised to turn a particular shade later. Pattern alone also cannot tell you whether a fish is healthy. When choosing a koi, observe how it swims and review the practical guidance in Buying Healthy Pond Fish.
Enjoy the fish in front of you
The quickest Kohaku check is a white base with red markings and no defining black pattern. From there, describe the individual arrangement of red rather than trying to force it into an idealized template. For more on caring for koi once they are in your pond, see Keeping Koi and Pond Fish. You can find other pond-care topics in the PondScape Learning Center.