Red claw crabs are slightly brackish, but for the "freshwater crabs" you need to get an exact ID on them as they could be anything, there are loads of types of crabs out there. Check out this site for more info on crabs;
http
/www.shrimpcrabsandcrayfish.co.uk/Sh...p.htm~mainFrame
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some nice pictures there, but the information on the crabs is way off.
this guy lists brackish crab as fresh, and seems to have real problems working out temp too.
the redclaw crab is brackish, no matter what this dude says, it needs land more than freshwater. they will live happily, in a freshwater setup as long as you give them, a dry area and a small brackish bath (1gram to 1 litre will be ok).
most freshwater crabs grow BIG (8 inches across). lol and need to be kept on their own!!!!!! they tend to destroy everything, plants other crabs and fish. they will mangle a set of ss forceps if you leave them in long enough.
to recap:
if you like crabs the freshwater type may be for you. they grow big, but need to be on their own, they too are land animals, so need a dry area about 2/3 of your tank floor. fascinating to watch, as they move everything they can around the tank.
if you are looking to keep crab in a community. my recommendation would be the redclaw crab. in my experience they get on well, with most inhabitants. they tend to be mostly viggie. and tend to be more concerned with their own safety, so in most cases are no threat even to little 1-1/2 cory. mine even get on with the Crayfish!!!!!!!!!!!!!! often forgotten fact about redcrab is their size, a big redcrab grows to 2 inches! most are smaller. they are entertaining, and very efficient tank cleaners.
my advice would be to avoid fiddler crab for the community. they are grumpy critters and whilst being good fun really need a tank to themselfs, say 5 in a 24x12x18 inch tank with 2/3 dry and 1/3 wet.
hope this helps!
