What can change color pattern of koi?

Feeding to enhance color koi fish are highly valued for their color and certain additives can be included in the diet to maintain and enhance the fish's natural coloration.
=Carotene affects the red pigmentation, but if used at too high a concentration, even the white pigment on the koi fish will turn pink.
=Spirulina platensis also enhances and fixes the red pigment, but does not turn the white to pink to the same extent. It is a type of algae found and cultured in Mexico and eaten by the people, since it contains a high level of protein.

Strong red and yellow pigments develop well in waters rich in green phytoplankton. Black pigment is enriched in hard water with a pH level of 7.5-8.5. Remember, however, that changing the pH and hardness of the water can affect the toxicity of ammonia and nitrite.
Good coloration is not only enhanced by good feeding, however. Healthy fish tend to have much brighter colors than diseased ones. To bring out the color in koi fish, particularly the white, you must provide good living conditions.

Please also visit our Koi Fish Tips for more information