Alright, I've got a new theory for the different colors of YWG.
It occured to me today that it could be based on how much time the fish spends in or out of the light.
My reasons for thinking this:
1) Our (proven) male spends ~99% of his time in thier cave, only coming out when the female lets him come out to eat and he is very much yellow-green.
2) Our (proven) female spends a large majority of her time (probably >75% of the 12 hour photo period) out side of the cave (begging for food
) and she is very grey-green.
3) I have been watching our babies that are almost 12 weeks old slowly changing in color from yellow-green to grey-brown over the last month or so. Right now there is not a single yellow-green one in the tank. They have a photo period of ~16 hr/day and no place in thier tank to get out of the light, only some small clear plastic tubes to cut down on aggression.
4) A little over a week ago I took a baby that was very much grey colored to put in my nano reef at work (yes this was authorized by Amy). This baby spends all of its time in a cave and only comes out to eat when food is put in the tank (2X day). In fact we couldn't find it for the first 5 days it was in there but finally spotted it coming out of its cave when food was put in. This baby is now almost completely yellow-green again.
So to prove/disprove this theory, I would appreciate it if all those that have a YWG could post what color theirs is and a guestimate as to the % of the photo period they spend outside a cave in the light. I am also going to put some sort of small caves in our growout tanks and see if the ones that hang out in the caves return to the yellow-green color. This is important as I am sure it is going to be easier to sell yellow ones than it will be to sell grey ones.