Can someone identify this crab?

[cyberchef]

I have 3-5 of these crabs that I know of. They just keep busy all day long eating algae and such off of the LR all day. I've never seen one even try to go after anythiong else in the tank.

[cyberchef]

Here's one more of it.

[FLHT]

Five of them? What did they do, come in on
some live rock?
I'd keep a close eye on them. Many people
hate the critters. Personally I think they are
more of a danger than what they are worth.
Good luck.

[FishDaddy]

Cyberchef,
Looks like it could be one of the shore crabs or a boxing crab....there are so many species and my references don't have an exact match from your picture. A picture of the top of the shell would be helpful. One of the real experts on the board may be able to tell.

Baensch Atlas, Vol. I, p. 656, shows a Liomera sp., Red Boxing Crab that is similar except for the coloration of the claw tips.
Here's a Rough Shore Crab (Cyclograpsus granulosus)

I'm certainly not expert but these are what I could find.

I would be very cautious. Regardless of the species ID, most all crabs are omnivorous scavengers that would not be above taking out a fish or anything else they could capture, once whatever they are munching on now runs out.
Dick

[Spanky]

Just a guess, Mithrax forceps. Red Clinging Crab.

Jerel