Can anyone identify this crab?

[Captain Squid]

Was a hitchhiker on a rock, started out small but getting bigger, now the size of a half dollar. Had a firesfish wake up with part of its tail missing. Friend or Foe?

TIA

 

[es1887]

i would say foe. most crabs are voracious carnivores. they will eat anything they can get their claws on. some people keep them in their tanks, but they also feed them a lot. if you are gonna keep it i would say make sure you feed it plenty and hopefully it wont eat anything in your tank. i have had a bunch of these types of crabs hitchhike into my tank, but i have always removed them when i found them. i never flushed or killed them i just put them in my fuge/sump where they couldnt eat any fish or corals. i even took one to my lfs.