Koi's yellows fading to gray

[vequalsir]

My father in law has several koi with yellows in his pond. He has noticed the yellows in those fish fading to gray color.

Is it a sign of age? The koi in the pond are very old.

Here in Ohio we just slipping out of the clutches of winter. He has cleaned out the filters and fired up his UV light. The water is crystal clear and the fish are eating well for it still being rather cool.

Looking for some ideas...Thanks

 

[turtle99]

koi and goldfish can change colours climate change and age can affect this.

 

[avanc]

I second the age thing, my goldfish slwly lost most of his gold as he got old, he was still perfectly healthy though apperantly they can go grey too.

 

[Ichthius]

Often yellow is a result of pigments in the diet. Might try color enhancing foods to see if the yellow will come back.

 

[vequalsir]

The Koi are about ten or years old. Perhaps this is just a diet issue.