Zfunk, that line you circled is their backbone, it gets more prominent if they lose weight. How did you circle it?
As for sexing them thats easy but it may not do you any good, I am not sure just any pair will become a "mated" pair. I followed them for a week in Bora Bora and the male (I think) seems to lead the female around the reef with a lot of distance between them like 20 yards. The male finds food and when the female shows up he goes cruising again to a new spot. They travel a lot and are hard to keep up with. Maybe thats the reason some of them are hard to get to eat, they need to be led to food? Just a theory.
Here is a place in Bora Bora where I followed a lot of Idols.
I think thats my wife in the picture.
Paul
