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Koi Color Changes

Koi Color Changes

They say a tiger can't change its stripes - but did you know koi and goldfish can change their colors?

As you get to know each one of your fish personally (and you will if you haven't already!), you may notice changes in the pigment, color depth and hue in the fish's black, white and red scales. Don't worry: It's not necessarily a cause for panic. The color changes can be caused by several factors, including:


Fish experts will tell you how critical a role genetics plays in the coloration and patterning of koi and goldfish. Dominant and recessive genes dictate how much hi (red), sumi (black), shiroji (white) and other colored markings appear. Some of the stand-out types of koi 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.


If your fish are stressed, their coloring may show it - just like when you take on a pallor-type tone when you're under the weather. Make sure to keep your pond clean and well-oxygenated with an aeration system, like the The Pond Guy Pond Aerator. Also be sure to check your water quality with a water test kit, like the Pond Master Test Kit that measures ammonia and pH, and correct it if necessary. Additionally, to give your fish the ability to keep stress at bay, The Pond Guy Stress Reducer Plus helps to restore its natural slime coat - while removing chlorine, chloramines and heavy metals ordinarily found in tap water. While Stress Reducer Plus is great for new ponds, regular treatments will help to keep your fish happy and well.


Fish - just like humans - are affected by what they eat. Feed your fish food that has enough vitamins and nutrients to support vibrant color, like Growth and Vibrance Fish Food. It contains top-quality ingredients, vitamins, natural color intensifiers and chelated minerals that enhance colors in koi and goldfish. To punch up your fish's colors, even more, add some oranges and watermelon to its diet.

Sun Exposure

During the summer when the sun is shining, you get a tan; during the winter, you don't. It's the same thing with koi. Their scales can change color depending on their exposure to that bright orb in the sky. They won't turn an Oompa-Loompa orange during the summer (though that may not be a bad thing to some koi keepers!), but you may notice a color change in some of your fish after their winter slumber.