Is 5-6 inches too early to sex? Maybe it's the angle of the picture, but from the length of the pectoral fin, it looks like you may have a female. Any more pics of it, specifically from the top view? Hopefully as it gets bigger, it'll become more round (and gravid) and you can confirm its sex.
So what are you feeding yours? Mine don't seem to touch veggies (except the coconut fibers from the coconut caves).
(I have 3 small ones (SL 2-2.5 inches) and 1 larger one (SL 3-3.5 inches); one of the small ones and the larger one has the same coloration in the pic, one is L-600 (all orange tail), and one is "blonde" lighter in color and some spotting in the caudal fin).