Possible crab ID?

[RTanger]

I don't know for certain if this is the correct forum for this, but it seems the closest for my question right now. Apologies if it isn't the right area.

So, to make a long story short, I ended up with a pet crab today at work. I am stuck on an ID for what kind of crab it is, and whether it needs fresh or salt water.

Edit: I guess I should add here that it has been living in fresh (well, to be honest, tap) water for close to a week now. The girl who brought it into the aquatics department kept it in a dish and fed it balogne...

It's tiny, maybe an inch to an inch and a half in diameter not including the legs. It has a red carapace with a large dark, almost black area on it's dorsal side that starts on the anterior (it's black from the eyes back) but this color fades to red at the posterior end. One claw is slightly larger than another, and both are white.

This crab was "rescued" by another individual at a sushi restaraunt, if that helps at all.

Thanks for the help!

[XnSdVd]

It'd really help if you could post a picture of it. As for it coming for a japanese restaraunt... I don't think crab was ever part of traditional sushi until "crabsticks" came about...
Might be a mudcrab of some kind... especially with the 1 larger claw or it could be that the smaller one is new.

[hwchoy]

they've always had those softshelled crabs on the menu, what.

[XnSdVd]

What i meant was they probably aren't a japanese species. I'm guessing softshelled crabs are pretty new too...I could be wrong of course =)

[RTanger]

I've already established it isn't a softshelled crab, it doesn't look anything like the pics I found of those, and it has a very hard calcareous shell. Not shrimpy. I'll see about getting a pic of it up by tonight sometime. Need permish to use the roomie's camera...

However, I did stumble upon this picture which is very close, if this crab's claws were just a little bit bigger and white, and the dark color on the back of the shell went all the way up around the eyes, this would be the crab I have.



Also, if this helps at all I have established that it spends most of the time out of the water, retreating to the water mainly when startled.