What type of crab are these?

[reefames]

They are navy blue with red legs and a giant 'don't mess with me' claw..
I picked up three of them at Petco last weekend. They hang out on the tops of my live rock, (they move around plenty also). They have no interest in the flake or brine shrimp food that I feed my fish. What do they like?

 

[reefman]

fiddler crab

 

[Josh]

I'm pretty sure those are brackish or freshwater fiddler crabs. They won't last too long in a saltwater reef tank.

They will eat meaty pieces of fish, clams, etc.

 

[tacson]

thats ahm hellboy crab