Q: I just saw my favorite koi. He used to have black spots – but where did they go?
George – Price, UT
A: Koi aficionados call their fish “living jewels” for a reason. With their rich red, brilliant white, velvety black and shimmering metallic scales, these swimming beauties resemble vibrant precious stones that glisten and glimmer as they glide through the water.
Thanks to generations of careful breeding practices, koi hobbyists have developed more than 20 varieties of nishikigoi (brocaded carp) that differ by their scale color and pattern. Some of the stand-out types include:
- Kohaku: White body topped with large red markings.
- Sanke (Taisho Sanke): Similar to the Kohaku but with the addition of small black markings called sumi.
- Showa (Showa Sanke): Black body topped with red (hi) and white (shiroji) markings.
- Ogon: Metallic scales in one solid color, usually orange, white, silver or gold.
A koi’s color pattern is dynamic through its entire life; the colors and markings change as the fish grows in size and loses and regrows its scales. For instance, a black spot on your Sanke’s back may seem to shrink or disappear beneath its red markings – only to return a year later in a morphed size or shape.
Bring Out the Brilliance
Though it’s part of a koi’s DNA to change its spots, environmental factors can cause modifications as well. Poor water quality, parasites and fungal infections, for example, may fade scale color. Insufficient sun exposure during the winter months, too, may cause colors to wane. But once the water quality is back up to par and sunless sky gives way to bright sunshine, those brilliant colors will return.
On the flip side, some external factors can actually enhance a koi’s color. Fresh vegetables and citrus fruits, like green peas, oranges and grapefruit, can bring out the vibrant red and orange tones, brighten the whites and deepen the blacks. You can also find commercial diets that are packed with ingredients, like vitamin C and spirulina, formulated to boost color.
As warmer weather approaches and your fish start to get hungry again, start them off with an easy-to-digest wheat germ diet, like The Pond Guy Spring & Fall Fish Food, followed by a higher protein, color-enhancing diet, like The Pond Guy Growth & Vibrance Fish Food. Also test your water quality and do what’s necessary to make sure it’s the best it can be. In time, you’ll likely see your koi’s black markings return – or change into something completely different!
Pond Talk: What changes have you seen in your koi’s color and markings?