found Xanthid crab in reef tank

took him into the lfs and he told me it is an emerald crab and is reef safe. water tested out good he told me "oh ya fish die sometimes" WTF??? he showed me some of his emerald crabs looked nothing like my guy. I really hope it was him but time will tell.
thanks for all the help

 

I have never seen an emerald crab look like that or have black claws.

 

Needles to say I would not deal with the guy that told you that at your LFS and I have also heard to stay away from anything with black claws.

 

Yeah that is not an emerald crab for sure. But I doubt that crab has slaughtered fish that fast also. Now a green terror star could maybe do that but not a crab that size.

 

It sounds like the fish may have died on thier own the crab was just getting an easy meal. he wouldn't have been able to catch those fish.

 

Did you move this tank?

 

Bingo I think, I have to ask what your amonia nitrites and nitrates are at...

No crab is going to kill other fish while he's still eating on one. Stranger things have happned though.

I'd guess you had a spike in parameters, the fish died, and viola the crab gets caught eating a free meal. With that said, the crab in the picture DID have what looked to be sharp claws and that's usually a sign of a predatory crab.
Better to be safe than sorry but I would definitely test your water. If it's out of whack I'd just sit and wait for it to cycle...

 

yes the tank was moved about 3 weeks ago by fishmax. i have been taking the water every 5 days to get tested and they say its test out good. I am having them come out and do a service tomorrow and will have them list what my tank has to add to my profile. the guy at fishmax who has been taking care of this tank for 2 years now also said he doesnt think it was the crab. but he got the boot from the tank anyway.
thanks for all the help. if anyone has RO system questions send them my way as that is my line of work, be glad to help.