My emerald crab died :(

[djs4him]

My tank:

180 gallon
No fish right now
Live rock
Nitrates: 10ppm
Calcium: 500ppm
Alkalinity: 11.6 dkH
Temp: 80F

I bought 3 emerald crabs yesterday from my LFS. They were all very active at the store and very active in the bag. I temp acclimated them for about 15 minutes and added them to my tank. The LFS manager assured me these little guys were "super hardy" and "almost impossible to kill".

Well I killed one.

This morning, an emerald that had been nibbling on some nori the night before, just fell motionless off his rock onto my sand bed. Within literally seconds, two of my nassarius snails descended on his body and enjoyed a pleasant lunch.

I don't get it. Especially since I was told they are little battle tanks. Not to brag but surely my tank is nicer than the one they come from at the store. Are emerald crabs easily stressed?

 

[PeterEde]

11.6dKH?
Just my guess is the crabs came from a much lower ALK and the 15 minutes is borderline. I would think.
Do you have live rock? Any chance of a pistol or mantis shrimp?

 

[djs4him]

11.6dKH?
Just my guess is the crabs came from a much lower ALK and the 15 minutes is borderline. I would think.
Do you have live rock? Any chance of a pistol or mantis shrimp?

I have live rock but no shrimp at all.

As a small update - my second emerald died last night as well. I'm down to one left. Are they maybe starving? Would they die that quickly if they weren't getting fed enough though?