Achilles tang locale, maturity or gender difference?

[MrCaveman]

I have had my Achilles for about 18 months now, got him when his orange teardrop was just small line. Recently I've just started to notice the difference between my Achilles with a white chest area compared to Achilles I see at my LFS that are all black.
Here's my fish; you can see the white pectoral area:


Here's the more typical all black Achilles:
http://www.bing.com/images/search?q...de732aeb8e834ec168eb49cfc7dd2763H0&ajaxhist=0
http://www.bing.com/images/search?q...ce00429e14fc10e55756bb1900065d6eo0&ajaxhist=0
http://www.bing.com/images/search?q...cc7e99fb143dbdabfd89d5938b516f45o0&ajaxhist=0

 

[Dmorty217]

Hard to say for sure, could be stress related or gender related I suppose. It's always there some just "flash it" more than others

 

[jbvdhp]

I had one that didnt make it in QT, and one currently on hold for me at LFS. Both had/have the white area