Mystery Crab ID Please

[Tetra1]

i have a mystery crab that came in with my ulva lettuce a year ago and he was tiny. I caught him today as I was breaking down my old tank and I am trying to decide whether he goes back in the new one. I don't want a pest in my tank do if you can tell me what he is id appreciate it. Thanks.

 

[AdamNC]

Kinda hard to tell. If the claws are sharp and pointy it's usually bad but if they have a scoop on the end similar to an Emerald Crab it "should be" reef safe.

 

[Calappidae]

White tip claws,

Appears to be a mithrax sp. However even emerald crabs can't be 100% trusted. I would sump it anyway, just because crabs in general are oppertunistic, however it's more than likely just an algea eater.

 

[rt67ghy]

I have one which looks just like that and i think it's cute. It hides under the tentacles of my torch and eats algae off the rock it's on.He has grown from 1/4" to 3/4" in 8 months and he hasn't harmed any of my corals.

 

[sam.basye]

+1 I've got two that don't bother anything and are a great addition. They are fun to watch as well.

 

[Umbra]

Crabs are hit or miss generally and IMO can't ever be fully trusted.

 

[rssjsb]

Kinda hard to tell. If the claws are sharp and pointy it's usually bad but if they have a scoop on the end similar to an Emerald Crab it "should be" reef safe.

Yeah, that rule doesn't really mean much. With the exception of porcelain crabs and other filter feeders, most crabs are opportunistic, as Joe says upthread. I would watch it and be prepared to sump it if something is amiss.