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Color in Koi: The best and the Brightest
By Joel Burkard/Pan Intercorp

Not everyone cares about perfection, but many are driven in their relentless pursuit of it.. Editors and English teachers won't accept anything less than perfect grammar. Figure skaters train for years to make each move precise and graceful. Gourmet chefs anguish over perfect flavor combinations and beautiful presentations. That's how much koi enthusiasts care about the color of their fish. Koi are prized possessions, "living jewels," and their colors are the crown jewels in their development.

Color in our koi is part nature and part nurture. Sakai of Hiroshima, one of the world’s most respected breeders, has said that the secret to producing great koi is ten percent genetics and ninety percent in the rearing, No matter how much food you feed, how big a pond you have, or how high-end the filtration system you install, you will never change a pond puppy into a Grand Champion. You can, however, transform a good koi into a stunning, award-winning koi. What does it take? Good genetics, good nutrition, good water quality, and plain old fashioned good sense.

Starting on the Right Foot (or Fin)

If you want a koi that will have vibrant and stable color over its lifetime, you have to start with good bloodlines. Most commonly, koi lose color simply because they are from a weak gene pool. It takes many generations of selective breeding to establish a strong bloodline that will perform consistently and hold it’s own over time. Discriminating koi keepers have learned that it is usually better to invest in one or two high end koi than in a number of lesser quality koi. These koi command a higher price because their heritage can be traced and documented, making it possible to gauge how their growth rate, colors, and body conformation are likely to develop over time. With the right kind of care and environment, bloodline koi will improve steadily and will retain their beauty through maturity, providing many years of enjoyment.

Most inexpensive koi are produced in large quantities to satisfy the demand for something that is bright and flashy, or for “instant gratification”. Koi from inferior bloodlines are easy to breed. They're also easy to sell, especially when they're young, small and still good-looking. This doesn't make them bad fish. It simply means, that because they are not bred from established bloodlines, they will likely lose color as they get older. Fish from unstable bloodlines tend to peak in their first two years of life. They look great when they're six to ten inches long, but after that they tend to fade rather drastically.

Food for Thought

Ever wondered why koi just in from Japan always have such fabulously bright colors, only to fade from red to orange after a few months to a year in a North American pond? Odds are, the koi have been getting lower quality food since they've come to this country. Prepared fish foods can be scientifically designed to enhance koi's growth, health and color. Color enhancers in fish food are extremely important. The koi have to be fed the nutrients they need in order to build and sustain their colors. (Some purists think koi don't need color enhancers, but they're koi keepers, not koi breeders. The only Japanese koi breeder I know who doesn't use color-enhanced food in Japan is Omosako. This is understandable, since he only breeds Shiro Utsuri (black and white koi), which don't need color enhancers.

Creating good color in koi is like creating good quality Japanese lacquer ware. The lacquer ware has a lustrous look and very deep colors. This is achieved by putting layer upon layer of lacquer on the object. Koi are much the same. In order to make their color deep and lustrous, it's necessary for them to put on layer after layer of color, year after year. This can be achieved by the use of a quality koi food that includes color enhancers such as carotene and spirulina . This can't be done overnight. It takes time for the color enhancers in the fish food to show any noticeable results. And there's more to improving color than simply feeding koi a single kind of food all year long.

Most color enhancing koi foods are high in protein and can only be fed effectively (in large amounts) during the koi's prime growth period from July to August. If you don't feed color enhancing food during that period, you miss the window of opportunity for color building and will have to wait until the following year for the next cycle. Overfeeding color enhancers can adversely affect the white background on your koi, giving the white a yellowish, or greenish tinge. This discoloration is usually temporary and will diminish with time and as the water temperature goes down, assuming you cease feeding the color enhancers. Feeding high protein foods when the water temperature is not high enough, can result in obesity, liver failure and death.

It goes without saying that you should feed a reliable, high quality fish food to your koi at all times. Select a premium brand that is well established, from a company that has done research on koi food. Read the list of ingredients, know what you're feeding your koi, just like you know (or should know) what you're feeding your children.

As you feed your koi, bear in mind that their color changes according to their growth cycle. In the summer, for example, koi are at the height of their growth stage and tend to stretch out. This stretching tends to make their color stretch out, too. If you try to make your koi to grow too quickly, you can actually cause them to outgrow their color. Once they lose their color, it will never return; the results are often irreversible.

What does this mean for koi keepers? Don't overfeed your koi. Koi that look like little footballs, aren't fat and happy. They are obese and suffering from liver degeneration, a condition that can be fatal. Make sure your pond is deep enough for your koi, too. Large koi especially, need deep ponds in order to develop muscles that can only grow when the fish swim up and down (not back and forth in a shallow pond). Eighteen inches of water is much too shallow for a fourteen-inch koi.

Although I don't recommend under-feeding koi, I should add that color can be intensified by stunting a koi's growth. When a koi stops growing, its color tends to deepen. Skinny fish can often be very brightly colored. Once you bring them home and feed them they start to gain weight, and can lose their color if not provided with an adequate diet.

Cool Water, Warm Water

In what may seem an anomaly to some American koi keepers who are used to attending North American koi shows in the summer, the most important koi shows in Japan are always held in November, December, and January. There's a good reason for this timing. It is in the winter months, when water is coldest, that koi look their best. The cooler temperature causes them to stop eating, and their color intensifies as the whites become whiter and the reds become redder. This winter intensification of color holds true for Showa, Sanke, Shiro Utsuri, Kohaku and virtually all varieties of koi. The colder temperature has a noticeable effect on the sumi (black) causing it to deepen and darken, and shine like liquid laquer. Omosako's Shiro Utsuri koi look fabulous in winter. In the summer, the warmer water causes the same koi's sumi to fade and become indistinct, losing the crispness that it had during the winter When thinking about color and seasonal changes in water temperature, the general rule is simple: cold water enhances color, especially black.

All Stressed Out

Any kind of stress can cause koi to quickly lose their color. One of the most common causes of stress is poor water quality. If your water looks clear, don't be fooled into thinking that nothing can be wrong with it. pH and ammonia can test normal but there are all sorts of other kinds of toxins that do not show up using the average test kit. Make sure to test for organophosphates, hydrogen sulfide, and heavy metals. Most importantly, use your koi as your barometer paying special attention to their behavior. They will always let you know when they’re not feeling well if you know what to look for. Are their fins or their fins flushed or pink looking? Are they scratching their sides against the bottom of the pond? Are they gasping by the waterfall or hanging listlessly in the water? Look at your filter. Is it large enough? When is the last time you cleaned it? Did you turn off the filter for nine hours when it was 80 degrees F outside and you were cleaning around your pond? Worse still (don’t laugh) are you one of those frugal folks who turns their pump off at night or keeps it on a timer to save on electricity? Maybe there's not enough oxygen in the water. That will certainly cause the koi to lose their color quickly, if they don’t die first from asphyxiation.

A Note to Control Freaks

Don't try to control the water. Only Neptune can control the water. If your pH is normally at 8.1, don't succumb to the temptation to change it. Every time you cause a pH swing, you are adversely affecting your koi. More damage is usually caused by pH fluctuations than in pH that is stable, but slightly high or low. Koi will usually acclimate to a pH that is slightly off from optimum, but can't acclimate to pH swings. If you're always bouncing it back and forth, your fish are going to suffer. If your koi look like they're not at their best, don't start fooling with the pH or doing massive water changes. Instead, add some salt to the pond, stop feeding the koi for a few days, and wait to see if they improve.


Spawning is probably the most traumatic thing that can happen to a koi. This brutal process can be a major cause of stress and loss of color. As the female comes into her time, every male chases her relentlessly around the pond. Each will pound her into a corner and squeeze up against her until she releases her eggs. Needless to say, this is extremely stressful, even fatal, especially for female koi. Compared to all the other risks associated with spawning, the koi's loss of color is really the least of your worries.

Although color perfection may be the goal, try to keep your efforts moderate. Just as over-practicing will cause injury to that figure skater, excessive measures to brighten color will have negative effects on your koi's health (and your sanity). Keep it simple, use your common sense, and your koi will be the better, and the brighter, for it.

My Fish is Losing it's color, What Happened?

Poor genes. If you want a reasonable idea of how your koi will probably develop color as it matures, buy from an established bloodline. If you don't care how the color may change over time, the koi's parentage is of less significance (although the heritage will tell you other things as well, such as how healthy the koi will be and other important considerations).

Poor nutrition. Feeding koi inferior food is one sure way to guarantee that they'll lose their color and shine. Koi have specific needs for color enhancement in the summer, and good koi food manufacturers have done their homework to provide us with sustenance that will make our koi as bright as they can be.

Warmer water. Changes in water temperature cause fluctuations in the color intensity in koi. Generally, cooler waters make colors more vibrant, while warmer temperatures make colors more muddled and muted.

Stress. Anything that can stress a koi, be it poor water quality, sudden changes in pond temperature, or transport of the koi from one pond to another (with different conditions in the two ponds), can cause koi to lose their color, sometimes even overnight.

Sex. The stress of spawning can be very harmful, even fatal, especially to female koi. Besides causing the koi to lose their color, it can cause them to lose scales, fins, and chunks of their body as they ram into each other and the sides of the pond. Males have been known to pester females to death. Sound Familiar?

Optimum koi color is possible following three simple guidelines:

  • 1. During peak growing season, feed a premium color enhancing food that's manufactured and sold by a reputable source. The rest of the year, feed a premium koi food. Don't overfeed your koi, as it is a cause of stress. Both stress and unbalanced nutrition can affect general health as well as color.
  • 2. Maintain good water quality without being manic about it. It's important to have clean, clear water. It's also important not to fiddle with things. Leave your pH alone and the koi will probably adapt. If your pH is so bad (acid or alkaline) that the koi can't adapt, then you're better off raising other kinds of fish (like plastic ones, perhaps).
  • 3. Have fun! Remember, this is a hobby. If you're not enjoying yourself, something is wrong. When something does goes awry, look first for user malfunction. Perhaps you forgot to clean the filter. Maybe everyone in your family thought they were the only one feeding the fish. It's usually something simple to discover, and equally simple to fix.

Copyright:2003 Joel Burkard/Pan Intercorp
All Rights Reserved


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