Freshwater crab ideas?
In an attempt to help keep my tank as clean as possible, I would like to get a couple of crabs. I've read that they'll eat just about anything, and between them and snails, I should be able to keep the tank that much cleaner. Granted, they will eat snails, but that's fine too.
The only one I've found any info on is the Red Claw Crab, but it's meant for brackish water and this is a freshwater tank. Some resources say they'll be fine in freshwater, while others say they really are better off in the brackish. I certainly don't want to put crabs in the tank and have them die.
I'm not just getting crabs for cleaning abilities, but I think they would be fun to watch. The only fish I'm concerned about are maybe the two guppies we have. Everything else is big enough or fast enough where a crab would be hard pressed to catch them.
Are there any freshwater crabs out there that are pretty easy to find in a store and can live entirely in fresh water without needing to be on dry land? I've also heard they are good escape artists and I don't want one of my ferrets finding a crab on the floor somewhere if it gets out. The ferret won't be happy with being pinched by claws and between the four ferrets, the crab won't survive.
Does anyone have any freshwater crab advice? I know even less about these than I do about tropical fish.