Can Ogon Change Color?

I know Ogons are metallic, solid color fish, but my friend recently gave me his platinum Ogon, and within about a week, it's solid gold now. It's a butterfly and I don't have any butterfly Golden Ogons in the pond, only a single Butterfly Platinum Ogon which is bigger by a few inches. I suppose my questions is: Can Ogons change color? I know certain water parameters can change the patterns and colors on a koi, but I never thought it could on an Ogon...

 

I would look into external parasites or velvet. It wouldn't surprise me if they can change colors, but that seems pretty drastic for a week.
Another guess is it got a sun tan??? I do know that they can get sunburns, but that is usually a more reddish color.

 

Yeah, I'll continue researching it.

 

Rich color changes can be fairly dramatic under different water conditions. Hard water can dull colors. I have that problem with my aquariums.

 

Yeah, I figured it was something like that. The water in there is very hard, as I intended. The fish is very healthy, it just looks different.

 

Can an ogon koi change color? Oh, definitely....
They can change color depending on the water conditions and light. But a part from this, every single koi can change color within a short time no matter their age. I've kept and bred koi ever since the mid 1980's uptill 2005. You'd be amazed how even a 4 foot long price winner kohaku can show a black spot in a sudden and becomes a sanke to give an example. Same goes for an ogon koi. No matter the size or age, a koi can change color.