Why do my emerald crabs keep dying?

[jerthunter]

I have had two emerald crabs so far, I had the first one for about a week, then he molted and never reappeared. Later I purchased a second emerald crab and he lasted probably about the same amount of time until he disappeared. I think he molted too but I can't be sure if the second one was a molt or a dead crab due to the location.
I do not seem to have trouble keeping other in habitants except for mexican turbos which die on me after a month or so.
Just so no one has to ask, I have a 65 gal tank, up for over a year, probably 100 lbs of rock and 60 lbs or sand (just a guess) No detectable ammonia or nitrites and for the last month no detectable nitrates or phosphates. specific gravity is at 1.025, temp 82 F, Calcium has been rather high from my salt mix about 500 ppm and my alk has been a bit low about 7.8 KH. I feed once daily and I have been adding SeaChem's ReefCarbonate to my make up water to slowly bring up my kH. I do not have any inhabitants that I would think would harm the crabs.
So is there any thing that I should look for that might be causing these wonderful creatures to disappear on me? I though perhaps a mantis shrimp but I tried using a trap and only caught a bunch of Nassarius snails and hermits so I doubt that is it.
Any help would be appreciated.
Thanks

 

[sinner's girl]

Calcium has been rather high from my salt mix about 500 ppm and my alk has been a bit low about 7.8 KH.

I do not have any inhabitants that I would think would harm the crabs.
what do you have? a star may eat a crab after it's molted...heck hermits might too...
how did you acclimate the crabs?
molted crabs look like the read thing, but if you look real close you normally can see inside....no eyes or whatever

 

[jerthunter]

I do have hermit crabs, mostly blue legs and zebras but I have one scarlet and a few misc hermits.
The first crab I acclimated for atleast 2 hours, the second I acclimated for only an hour since I was in a hurry.
I am sure the first crab molt was actually a molt, I could see that it was hallow, the second one I am unsure of because of the location I couldn't get at it to examine it closely.

 

[emmitt]

Hermits will not eat a live emerald crab unless the hermit is much larger than the emerald

 

[pandafish]

If you have some large holes in your LR they might be around still. My emeralds would "disappear" for weeks and reappear or I would catch glimpse of one in a hole moving around.

 

[jerthunter]

Originally Posted by Pandafish
If you have some large holes in your LR they might be around still. My emeralds would "disappear" for weeks and reappear or I would catch glimpse of one in a hole moving around.
Really? Thanks, that gives me hope, I figured after a week they were gone for good. I'll hold off on buying another one and hope one or both will reemerge.

 

[volcom69]

i feel special when i get to see mine i never do then one day i will walk by and there he is its weird, but i found out he is hiding under my mushrooms during the day though.

 

[toyshika]

They never come out during the day. I have five of them as of today. They like to hide inside the rocks...and at night...out they come. Sadly, since I've had them...my cleaner shrimp who is usually out and about...MIA for two weeks. I assume that something has occured in the tank with them! :-( He use to clean my hand everyday.... *sigh*

 

[metalhead]

your emrald crabs die because....you touch yourself at night

 

[sinner's girl]

being in a rush is a stupid exuse. don't buy the animal if you don't have time to properly acclimate it.

 

[jerthunter]

Originally Posted by Sinner's Girl
being in a rush is a stupid exuse. don't buy the animal if you don't have time to properly acclimate it.
I agree that proper acclimation is important and even though I was in a hurry I still acclimated the second crab for an hour which is what I understand to be the recommended time. I suppose my emerald crabs could have both died due to acclimation shock or perhaps MetalHead is right and that is why my crabs are dead. Although I really don't think either of those are the reason why. I am going to speculate that they both molted naturally and either got killed by other inhabitants while waiting for their new exoskeleton to harden or they are still alive and kicking hiding somewhere in my live rock.