Is this Green Chromis dying or pregnant?

Ok this is where I'm at with this. Friday night when the daylights were out I noticed one of the bigger Green Chromis' running back and forth across the front of the tank. Highly unusal as they always hang in the rocks or float in one of the corners. Saturday he stayed in the top left corner all day. Sunday he was gone all day. Today he is back but not swimming around as usual but rather hovering next to this yellow coral I have and frantically moving his gills. Now I do have a mantis shrimp in the rocks. Could he be permantly spoofed? Is she getting ready to breed? Is she dying? Anybody have any experience like this? Last week I lost the smallest chromis. He looked like he'd been attacked as the back fins were eaten up. I've had these guys for over a year and I'm puzzled. Here is a video I just took.
YouTube - Green Chromis acting wierd. Dying or pregnant?

 

Ok now for the past two days she's found another spot next to the overflow behind a rock. I think she's breeding? Anyone out there have any clue?

 

Sorry I have no clue, but one of mine has been acting the same way , and now is always hiding in the rocks.

 

mine did that for a few days and now it is dead but i dont know why so im interested to see what others will say

 

I'm hoping that she makes it through this but I'm ready to accept the worst.
One bright spot today was when she peeped out to eat some food.

 

Its fin looks damaged and to me looks like its stressed out to the max. Has anything been picking on it like I said I saw its side fin like its chewed up?

 

This is exactly what I'm thinking. It's got to be the mantis shrimp and I'm dreading what I'm going to have to do and that is to tear apart the reef to catch him and redo the rockscape. I have a toadstool that is firmly attached to two rocks and star polups everywhere. It's just going to be a nightmare but I'm going to make preparations with my LFS to have them bring me seawater to do a water change right after I'm done.

 

I do know green chromis will cull out the weakest in the group and so over time you may end up with just one well at least in my experience with them. So that might be your culprit too. Just a thought.

 

I agree with Scenario, that fish looks seriously stressed out and its fin is messed up. But you haven't seen him picked on? Could be happening when lights are out. My clown used to attack my damsel a lot. I wouldn't see it during the day, but the next day when I would turn the lights on, the damsel's fins would be all chewed up.

 

I haven't seen any of the fish attacking each other. I know it's true that fish will weed out the weak but I haven't seen it and I watch my tank closely. The mantis has to go!