Hi guys, I am moving from freshwater fish to freshwater crab.

My tank have been sitting empty (after my last betta fish passed on) with just a few nerite snails in it, water and filter is still currently active and running.

I want to do a revamp and convert it to a simple and drier (easier maintenance) setup and keep some freshwater crabs.

1) Are there any freshwater crabs available in Singapore that I can keep in a simple setup with sands, rocks and driftwoods?

2) Lets say there are no specific species of sand crabs available, can I get alternative crabs and rear them in a sand setup simple paludarium?

3) What type of filter is best? As there will be little water, say 80 dry /20 water ratio, does the filter need enough water to suck in so it can pump out? How do I this to work?

4) Are plants compulsory? I was thinking just sand, rocks, pebbles, and driftwood. Basically re-using my previous freshwater fish tank stuff.

For advise please, newbie in crab setup here really and want to make it work