Emerald Crab Losing Legs

I added an emerald crab to my tank a couple days ago and since then he seems to have dropped a couple legs. The tank has been set up for about 6 weeks and he was my first invertebrate. I acclimated him over a 2 hour period prior to putting him into the tank and my water parameters are as follows:
Salinity - 1.025 (measured with a refractometer, not a hydrometer)
Ammonia - 0
Nitrite - 0
Nitrate - 0
PH - 8.0
Temp - 78.6 F
Help! The ocellaris clownfish and my few coral frags don't show any signs of distress.
Not that I know of. The only fish is an ocellaris clown and he doesn't give the crab a second look. There are no other inverts in the tank except for some copepods, bristleworms various other itty bitty hitchhikers. I haven't noticed any clicking or popping sounds that would indicate a mantis or pistol shrimp.
Other than the missing legs, he doesn't seem distressed. He's moving around the rocks and picking at the algae.
Originally Posted by vinny p
maybe u got it like that from lfs?
He was missing a leg when I got him from the LFS, but he's lost a couple more since I brought him home. I'll just keep an eye on him. Hopefully it was just stress from being put into a new tank.