Taking care of a 'freshwater' fiddler crab?

They need water and area to come out of the water. They also need some salt. It is very hard to keep them healthy and they fight a lot. I had a very bad experience myself. I wish you good luck. I would set a tank with a filter in the bottom and rocks fro them to climb out some sand would be great and pebbles. Need to keep water very clean and need some salt. Some ignorant stores dumpt them in tanks with the fish they end up dying in the filter. It is very sad.