Is This A Bad Hitchhiker Crab?please Help...

[KittyKat]

I have this black crab in my tank that hitchhiked from the LR. Is this a bad crab to have in my tank and whats the name of it? Does anyone have any more closer pictures of this crab? Currently in my tank I have a few corals(open brain,donut coral,frogspawn,torch coral,colt coral, 2 different types of finger leather corals,some zoos and mushrooms, 2 fishes, about 6 hermit crabs, I did have 2 snails but I just found an empty snail shell with no snail in it, a cleaner shrimp, and a sand sifting sand star. When i was adding a new live rock in my tank i saw it come out but it ran away real fast and tonight I finally saw him posted up in one of my live rocks. It has been over 2 weeks since i last saw him and my main concern is if this hairy crab is going to do some damage to my reef tank.

I'd appreciate any info or advice on these hitchhikers. It really looks very very similar to WITFULL's pic he posted. Here's the link of the pic that he posted on this thread:



Thanks for any help.I'm a newbie in this and so far i'm loving it but there is always something new i learn about my tank everyday and today it was this mysterious crab hiding in my live rock.

3/22/08:This morning i saw the crab just a little bit and it looked like he was eating algae and whatever else he was picking off the rock he has been living in. I saw one of my hermit crabs come very close to him and he did not do anything to it so maybe he's not so bad to keep? Id really appreciate any help on this.

Thanks again!

[goldenmean]

Crab Hitch Hikers

it is hard to ID a crab with out a pic but as a general rule of claw.
If the crab is hairy it is a danger to reefs
if a crabs claw is black and pointy it is also dangerous to a reef tank.

[framerguy]

I have what can only be described as a "black" emerald crab. It looks like an emerald in everyway except color. If the claw has a flat, round tip it is designed to eat algae, and "should" be OK. As with everything concerning living creatures, there are good ones and bad ones, and ones that have been good can turn bad. I have kept a very close eye on my black emerald, and you should too, and remove it at the first sign of unwanted behavior. Try to get a photo of it for a definate answer though.

[KittyKat]

Here is a picture of the crab, thanks everyone for the help.

[rlf_racing]

That crab is still not safe. There is also nonreef safe crabs that have cupped claws. I would still banish it to the sump.

[lcstorc]

You mentioned that yours was hairy. Regardless I woild remove it to the sump or fuge. The only crabs allowed in my tanks are scaarlet hermits.