A kohaku koi with distinct black “bands” stretching across the body.
Many koi enthusiasts have trouble distinguishing between Showa and Sanke koi.
If the black markings appear as isolated spots on the koi, then it’s a sanke. If the black markings appear as large blotches or bands on the fish, then it’s a showa.
The showa, sanke and kohaku make up a group of varieties called the “Gosake trio”, which contains the three most common varieties of koi. Most other koi varieties are bred down from one of these three types.