Crab living in staghorn rock Good or Bad

[prowler]

I Have this crab living in my live rock it doesn't seem to be harmful to anything in the tank to my knowledge. If anyone can I.D. it i would be grateful.

 

[wade1]

Give us a few more details... size? Does it have hairs on its legs? Its in a rock, not living in live coral?

Wade

 

[prowler]

Sorry about the lack of a decent photo but he don't seem to venture far from his rock. He lives in one piece of rock. He has hairy legs, would be about 3 inches across his body not including his powerful looking claws. He is basically black in color with white in places with a sort of armour looking body you can see in this photo. I will try and get a better photo but he seems aware of my presence and darts back in the rock. I got hold of him with a pair of tweezers but lost grip of him and he shot back into the rock.

 

[wade1]

Based on the shape of the claws, it appears to be primarily a grazer. Notice the flat spots where the claws come together? Mithrax sp. crabs have those claws, they work well for pulling out algae. If you haven't noticed any lost fish or inverts, I wouldn't worry too much about it.

I would caution you though, because some of them can get big and once big enough, they might supplement their diet with something they catch. I'd leave it for now, but keep an eye on it.

Wade

 

[prowler]

Yeah i'll keep an eye on him thanks for the reply