increase surface agitation/add some air stones to increase the oxygenation of the water.
Nitrite impacts the fish's blood's ability to carry oxygen and could be why he is hanging at the top where the water is more saturated.
when you say the rest of your rock is "curing" at the lfs
, what do you mean? did you buy dry rock and they are culturing it for you or was it fresh from the ocean and needed to actually be cured?
If you bought dry rock and they are culturing it for you, they are just taking advantage of you as you would end up with the same result if you just put it in your tank from the start. If it's "live" rock to help get your tank established, why isn't it in your tank now when it is most needed?
Something seems a little fishy about that.
Yes, that is a bicolor. They have a distinct line differentiating the body color, in royal gramma's the colors merge into one another softly.
I would take what the lfs
tells you with a big grain of salt.
While hardy fish, those two are certainly NOT the first choices for doing a fish-in cycle.