Crab ID Please

[jonrath]

Bought this closed brain today and noticed this hitchhiker.  Think it might be a decorator crab??? It is about 1.5 inchs.  A COnfirmation of what type of crab it is and whether or not it is reef safe would be appreciated. Thanks

[Greatwhite]

Kinda blurry... It might be a harmless emerald mithrax crab..  If you can see his claws, that'll give you an idea of whether he's a good guy or a bad guy.  Emerald crabs have large, rounded tipped claws for picking at algae.  Bad guys generally have sharp, pointy claws for tearing bits of flesh.

[az]

I agree it looks like emerald crab.

[jonrath]

Here are a couple more pictures, again not great, but a good view of the claws.  They definitely have a greenish hue, but I am not good at judging rounded or pointy.  Would like to be 100% sure before putting him in the tank as I am sure I will never get him out once he is in there. I was reading about emerald crabs, it says they occasionally can eat small fish?  Is that true or are they "harmless" ?
Thanks for all the help, it really is great to be able to get advice from people with more experience.

[BOnaqua]

It looks wierd. Like 50%  emerald, 50% some other crab.
Based on claws, looks like an algae eating crab.

[Greatwhite]

Better pics helped alot.  I'm 99% sure that's an emerald crab.  Since you were able to catch him so easily, he was probably not too concerned about his fate.  A predatory crab would usually hide at the first sign of your approach.  My emeralds used to sit out in full view, and greet me.

Good hitch hiker.. Congrats!

That guy will climb all over your rock work, picking at algae and will devour any bubble algae that appears.

[jonrath]

Thanks all for the help the the emerald crab.  I put it in the display tank, and will see how it goes. I'll give him a chance.  I don't have a refugium yet, I plan on setting one up in the next few months and once I do I will put the hitchhikersin there. 
Tonight I found another hitchhiker crab in my live rock that i would appreciate an ID on. I have removed a few red eyed crabs from the live rock over the past few months but this one looks different.  It is smaller and more delicate looking and has stripes on its legs and claws.

[JetJumper]

I have one of those in my display tank and he hasn't hurt anyone yet.  I don't know exactly what he is though.

[Greatwhite]

I'm no expert, but this one looks like a bad guy.. I think some kind of xanthid crab... His small, pointy claws are good for picking at corals.

I had one like him when I started my tank a while back...  He's in a better place now.

[Greatwhite]

Keep in mind that refugiums are intended to give a safe place for pods to live & thrive.  Don't put predators in there.

[Darth]

that looks like a crab I had in my tank, it was huge when i got him out, I gave it to az