comet fish turning silver

Question
QUESTION: Hi there,
My kids have two goldfish and one comet happily cohabiting. The comet has turned silver over the last few days.  He's still very active and eating.  He's definitely over one year old.  Any ideas why?  They're getting quite upset about it!
Thanks.
Regards,
Debra, Essex.

ANSWER: Hi Debra,

As fish age they gradually begin to lose colour. However Goldfish are capable of hitting 20 years with relative ease.

Is he swimming with his caudal fin clamped and also can you give me an outline of his diet?

Cheers

Tom

---------- FOLLOW-UP ----------

QUESTION: Hi there,
Thanks for replying.  His tail fin seems to be moving freely.  We feed him on Aquarian Goldfish flake food twice daily.
Regards,
Debra.

Answer
Hi Debra,

Goldfish tend to fade with age. The Comets cousin the Black Moor begins life as a jet black fish, however it's belly turns silver as it gets older and settles into life in an Aquarium.

If he's feeding regularly and is swimming freely and frequently then he fits the bill of a happy, healthy fish.

Tom