Goldfish and their Coloring

Scruffy

I have had a few gold fish over the years and have always wondered why some change colors as they age. Is this part of them maturing?

Like the picture attached, this guy was all orange at one time and is now all white. I've had a comet that was a mix of black and orange, then turned almost all black and then turned completely orange.

I have always been curious if this was part of the aging process.

Lupin

It's quite normal for all Goldfish to shift colors. Genetics plays a major influence in this followed by the foods they eat and environmental conditions. Formally, it would be called or apoptosis or in layman's terms, cell suicide or cell death meaning the initial pigment cells die or fade away as a result of factors that influence this result only to be replaced by a much more different set of pigment cells.

You'll find more explanation here. It's quite a long story. Let me know if you have any further questions.
Developmental Color Change in Goldfish | Goldfish