Yellow watchman goby no longer yellow

[bluemon]

I've had some remain yellow but the one I currently have is the first that turned grey with black bars...

Mine always does this with age. All three I’ve had

 

[Zodiac]

I like to get fish small so I know that it will last longer, with a fully grown fish I wouldnt know how much time he has left. Unlike some tangs and others that you can tell the age by the colors/shape.

In this case though I would rather try to get an adult size fish that is yellow next time to increase the chances that it might remain yellow, if I can find one. I dont mind fish changing color or shape, but changing to white/grey/black is too boring.