General Crab question

[acidburn470]

I am looking for a relatively small crab to add to a 20L tank, I dont want one that will eat my fish nor do I wany my fish to eat it. I was thinking a Fiddler Crab
I have right now a German Blue Ram, African Butterfly, Leopard Bushfish, Golden Wonder Killie, Raphael Catfish, Betta, and two plecos. The tank also has a few plants.

 

[DNordbak]

I can't vouch for a fiddler crab, but I've had a red claw crab for a few weeks ago, and it seems to be doing really well.
Just make sure that you:
A: give it a place to get out of the water, since they like to be in the air for part of the time
B: seal up every possible spot for him to escape. Even if you think the hole is smaller than the crab is, seal it up.
Now, a lot of people are going to say "those crabs are brackish water", but mine has been doing really well since I've had it. As for feeding him, he just eats the scraps from the food (brine shrimps) leftover from when I feed from my puffer fish. And as for him being attacked by them, he has done a pretty good job of fending for himself, just a few pinches every now and then.

 

[Oddball]

The only fully aquatic freshwater crabs I know of will try to eat your fish at every opportunity. They will also shred all of your plants in short order.

 

[guppy]

I had some of those little brown crabs you see for sale from time to time for a couple bucks each. Never did know the species, they were at most an inch across the shell. the got the occasional guppy and the smallest one was munched by a butterflyfish but mainly they lived on top of the plants(elodea mats). The main worry was they like to go inside the filter and at night they would cruise around on the curtains but if you turned on the lights they would run back to the tank, I left catfood pellets on top of the tank for them.