clown getting black?

[GuppyGuy]

i have a clarkii clown who I've had for a few months now. He has progressively gotten darker coloring (black-ish) on his top half. Any ideas?
I was thinking it could be the food but I feed wide spectrum pellets and frozen on a regular schedule daily and my other fish don't show anything like this.

 

[davocean]

It's pretty common for some species of clowns to get darker or have the black areas become more pronounced as they age.
Post some pics.