Crab ID?

[Reeferbadness]

Not sure what this bad boy is. I believe I bought an emerald crab once but if it’s the same one, it’s 5x bigger. Reef safe ( so far ) but he does try to eat my fish ( unsuccessfully so far). Adult fox face for scale ( upper right )

 

[Brit’s Fish]

Looks like a Sally Lightfoot to me!

 

[sfin52]

Agree Sally light foot. They are a fish eater when they get bigger.

 

[WalkerLovesTheOcean]

Definitely not your emerald crab. I agree that it's a sally light foot, and it makes sense it's trying to eat your fish.

 

[Reeferbadness]

Thanks guys, it definitely looks like it's a Sally Lightfoot. Luckily the fish in that tank are all pretty large (Fox Face, Gem Tang, Meta Tang, Swallowtail Angel, large Sleeper Goby and a couple of others). Will keep an eye on him. He is a algae eating machine so that's definitely a plus. Hasn't gone after my cleaner shrimp yet either.

 

[Mark Goode]

I've a fairly large Sally Lightfoot, probably a couple of years old. It's a wonderful algae grazer, and a fascinating critter. The only thing it's ever killed was my other Sally Lightfoot, so I guess they're best kept singly.

Edit: It looks like yours has nothing to eat, so it will go for your fish. Give it a sheet of nori.