I asked dendroboard about crabs, but didn't get any replies from owners. Just guesses. I guess not many people are housing them?
I got a setup going in the making. I have got some clay, then soil with pennywort, creeping jenny, polkadot plant, pothos and some rosewood root, a random fish cave I found in the front yard, some random gravel and rocks, some leaf litter. All boiled or bleached except dirt and plants of course.
I am trying to find what else I need to do, like water feature or how often to mist. I am not in any hurry.