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We have one koi and about 14 fish that are comets or goldfish in a swimming pool converted to a pond. They are about 5 inches or so long at about 1 year of age. Very robust and active. Four of them are basically white. Of the four, two have some deep orange spots naturally on them. I just noticed today that the white on the fish is turning a washed out yellow/orange color. They were seemingly pure white before. Now fins and head particularly are turning organish. I'm worried about their health. One website that sells koi food says this is due to liver function. Can that be correct? If so, what do we change? We are feeding Tetramin and a special koi food.

We are in Hawaii so the temperature is in the 80's. Full sunlight on the pool. The pool is about 15,000 gallons with deep areas at 8' on one end. The water is not filtered, aerated or treated in any other way and is very green as my husband is under the impression that it is a large enough body of water to not need extra care. We have two water hyacinth plants in with them. The fish eat the fish food, algae and bugs that fall into the water. The comets/goldfish we bought were sold as feeder fish" and we put them into the pond when they were only a few inches. They are now robust in girth, about 5 long in the body and very active. But I wonder what this symptom may mean in terms of nutrients and water quality?

Answer 1:

It is difficult to say precisely what is happening to your fish because koi can change coloration for many reasons. Most of the time, color changes in koi are not a concern; part of the challenge for koi hobbyists interested in color is to figure out the right combination of diet and genetics to produce the most beautiful fish.

Koi obtain the pigments required for coloration through their diet. Orange and red colors are a result of the deposition of pigments (called Erythrin) in fish cells called chromatophores. Perhaps your fish have been consuming more Erythrin-rich foods, such as algae, than they had previously, which may be filling their chromatophores with red and orange pigments. It is also possible that the chromatophores have actually filled completely, and the fish are passing the excess pigment through their feces. When this happens, white parts of the fish become pinkish due to a build-up of red pigments on the outside of the fish. This pigment is NOT in the chromatophores and should disappear if the amount of color food given is reduced.

Please visit the following website for a very thorough discussion of color changes in koi:

color_changes


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