Actually it's more the other way around, far larger specimens in captivity than one will typical see in their native waters in Central America. BTW - the fish in the photo is most likely NOT a pure A. labiatus, so that picture adds zero to this discussion.
Check out the first 2 pics in the following past discussion.
http://www.monsterfishkeepers.com/forums/showthread.php?203143-Amphilophus-for-Cookiemonster!
I believe that wild caught lab was a solid 12+" when that photo was taken back in Jan. 2009, and when I spoke to Chris last year he told me that male labiatus was still growing. It's already easily in the 13-14" range, possibly larger.