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Is it normal for my koi to change color? Why does it happen? | Decorative Ponds & Water Gardens Q & A

Is it normal for my koi to change color? Why does it happen?

Q: Is it normal for my koi to change color? Why does it happen?

Judy – Southport, NC

A: They say a tiger can’t change its stripes – but did you know a koi can change its colors?

As you get to know each one of your koi 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:

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.

Genetics: Koi experts will tell you how critical a role genetics plays in the coloration and patterning of koi. Dominant and recessive genes dictate how much hi (red), sumi (black), shiroji (white) and other colored markings appear. And, just like your hair color can change based on your genetic makeup, the koi’s scale color can change, too.

Stress: If your fish are stressed, they may show their unhealthiness in their coloring – 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 Airmax® KoiAir™ Water Garden Aeration System. Also be sure to check your water quality with a water test kit, like the API® Pond Master Test Kit that measures ammonia and pH, and correct it if necessary.

Diet: A koi’s overall health – just like human’s – is affected by what it eats. Feed your fish food that has enough vitamins and nutrients to support vibrant color, like Pond Logic’s Growth and Color 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 koi’s colors even more, add some oranges and watermelon to its diet.

Pond Talk: What kinds of color changes have you seen in your koi?

Pond Logic® Growth & Color Fish Food - Enhance Fish Health & Beauty

24 Responses

  1. I had an all black koi except a smal band of white around his neck now he’s mostly white with just a little black

  2. Hi, I have Koi Betta fish. My gorgeous male has turned all black except for his head! He’s still the cutest thing. Do you think it is stress, oxygen or genetics?

    • Hi Cathryn- This is hard to say without all the pond details but if you fish is still active and eating I wouldn’t worry too much.

  3. My koi was a beauitful yellow gold color and when i brought it home it turned orange and white im figuring its stress please let me know if im wrong!

    • It could be due to stress or just the growing process. You may also want to try feeding some citrus foods to help bring out the color.

  4. I had a small Koi I bought at a local pet store that was inside in a tank for about 8 months that was almost all yellow/gold color. After I moved it to our pond outside it has changed to a beautiful orange and black.

  5. One of my koi who is usually white with black streaks, now has an orange tinge, especially his head. Two other fish also seem to have an orange head, lately. Is this something I should be concerned about? I don’t find this description in any diseases online.

    • Hi Pamela – This sounds to be the result of genetics and environment. I don’t think there is any reason for concern with an orange color. Typically white fuzz, spots or red sores are indications of infections.

      • Hi,I have a bronze colored koi fish and recently I have noticed that my koi is losing her color from bronze to white…those that mean anything?….Please I need help before she dies

      • Hi Gerard – If the fish showing any other signs if illness such as lack of eating, clamped fins or flashing? Color change only does not necessarily indicate an illness. Feed a food high in protein or use fresh fruits with lots of citrus to help bring out color and be sure there is access to both sunlight and shade in the pond.

  6. Why when my koi change to white colour then after few weeks become weak and die?

    • Hi Joseph – Do you have a waterfall or aeration in the pond? Have you taken the temperature of the water? In this case it seems the color change may be due to a stress factor such as low oxygen.

      • Yes there’s aeration in the pond and tested water temperature are ok

      • Have you done any other testing on water quality such as pH, ammonia or nitrites? Is your pond new or were the fish recently purchased?

  7. We got a koi about 4in long. We bought it home put in our pond and never seen it again. Could it have changed color? We have only had it for 4 weeks. Never say it floating or in the filter. Where could it be.

    • Hi William – Depending on how friendly the fish was you first received it, it isn’t uncommon for the fish to hideout for awhile or be difficult to spot. Have you tried offering any food? I would start with just a small amount and you may notice the fish come out when you aren’t looking and eat. Are there any other fish in the pond? They love to be in groups and it also helps them become friendly quicker.

  8. Only one off my koi has begin to develop black dots on it. It doesn’t seem to affect the other fish.

    • Hi Terrance – Typically black dots are not a sign of an illness and most likely just a change in color due to fish age or environment.

  9. My koi is a silvery white and it’s eyes are all white. Just wondering if its sad or unhealthy?

    • Hi Jerry – If the eyes have developed a cloudy film it may be a bacterial infection known as Cloudy Eye. PondCare® MelaFix is an all natural antibacterial treatment that can be used to treat such a condition. Without seeing pictures or having a complete background of your pond and fish this is just an educated guess.

  10. maintain multiple koi ponds on eastern Long Island and have black Koi in several of them. This year as they grew bigger (12-15 inches) several of them have taken on a white marble look. At first I thought it was either a water issue or some other problem. Very happy to realize “it is what it is”. Feeding them a mixture of Dainichi growth and color pellets along with fruit, slugs, earthworms and assorted water plants.

    • Yeah, it is very scary the first time you experience it as you assume the worst. What a relief it is to find out that all is well though.

  11. We live in northern Virginia and the temps here have been in the mid nineties to over 100 degrees for much of late June and July. We have noticed that during the last two days our Koi have almost stopped eating and our mostly white koi has changed its pigment to orange. Do these changes indicate a problem?

    • Just make sure that you koi are have plenty of shade available via shelters and plants and keep an aeration system running as warm water does not hold oxygen very well. Your fish may be stressed from the heat which will cause them to not eat as much but unless they are trapped in a stagnant pond with no air they will be fine.

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