Fiddler Crabs

Okay, I'm convinced that its not a good idea to put a crab in my
aquarium--not because it might eat my fish, but because I saw
something that really bothered me in the LFS today.

There are two fiddler crabs (a male and a female) in a freshwater
aquarium that I looked at last week. They seemed fine the first time
I saw them and were entertaining to watch. Today when I went in, the
male never left the corner of the tank. He was constantly clawing at
the sides of the tank trying to climb up for several minutes while I
watched. The female at one point tried to climb over him as if to use
him as a ladder to get up the wall. I watched them both for a long
time and it just seemed that they were frantic to get out of the
water.

I know that they are known to escape from aquariums, but their
behavior was so different than it was last week. It just seemed they
were desperate to be out of the water. I almost wanted to buy them
just so I could set them up in a semi-aquatic environment but I don't
have a tank or anything to put them in right now. It made me sad.

Maybe I'm overly sensitive and this is normal crab behavior, but I
think it would be cruel of me to try and keep one in my tank. So
until I can dedicate a home for them alone, I won't be bringing home a
crab.