it's very important to only get;
Sesarma bidens aka
red claw crab aka
Thai red claw crab aka
Thailand red crab
AVOID FIDLER CRABS - THESE ARE FISH KILLERS
FEMALE FIDLERS ARE MISTANKEN FOR THAI RED CLAW'S
AS THE FEMALES DO NOT HAVE THAT ONE LARGE CLAW
Here is some Q&A with fish-lover some may find helpful;
do they like a land/water combo ?
yes, but they don't need land, just a small area to get out above water every few days. i have kept one totally immersed for a Month with no ill effect. I recommend at least having a few dense rigid plants growing to the water line such as Limnophila aromatica for them to climb, driftwood, or you can do my moss rope ladder.
what do they eat ?
plant debris, veggie pellet|flake food, cooked veggies.
recommended water supplements: calcium, *iodine, marine salt.
*iodine is thought to help ease molting. I have already lost one crab because he could not get out of his carapace,
so this is important. also make sure there are enough secluded spots in your tank where a crab can molt unmolested.
whats the minimum tank size they will be fine in ?
1 male per square foot of tank bottom, as many females as you like.
Where did you get yours ?
How much were they ?
Do they bite ?
no, and they have never pinched me either.
can they climb on glass ?
no, but on larger tanks with wide lines of glue in the corner, they have been known to climb up the glue.
-they will use tall plants against the glass, and your tank plumbing to climb out and escape, so plan your tank accordingly. i do not cover my tank with a canopy, but I do have a broad tightly fitted Plexiglas guard all around where my tank tubes and wires comes over the tank lip, and I keep my water line at least an inch below the tank frame, and keep waterline high plants at least an inch from the tank glass.
How big do they get?
2 inch square
regarding these crabs alleged aggressiveness.
I have timid African Dwarf Frogs, Ottos and Farlowella. I have repeatedly seen these crabs climb OVER my frogs and fish without so much as a pause to inspect what was under them. these crabs NEVER grab at nearby fish nor do they sit with their claws up and open hoping to grab something. I have a gang of endlers that like to eat the plant debris my crab kicks up and they buzz around the crab claws without the crab even noticing. the crabs will often hang around up and inside my plants looking for debris, and other fish swim right by them without a care in the world. males will briefly battle with each other when they meet occasionally disturbing a fine plant in the process, but so far after 2 Months none have lost any limbs (which is more than I can say about my crayfish). People who keep writing on the threads about aggressive crabs probably do not have this species. these crabs have a stubborn streak in them to hold their ground, so if a fish such as a pleco would push the crab out of the way, the crab may try to pinch the pleco in defense, but that's as nasty as these crabs will get. if you have other bottom feeders such as corys, loaches or eels, these crabs won't bother them, and even if the crabs in a foul mood those fish will easily get away. just be sure your tank bottom does not have too many inhabitants already competing for limited space and hidey holes
do not mix these crabs with larger crayfish as the crays will pull the crab's limbs off and eventually kill and eat the crab