Underwater crab habitat

[Spidyman]

http://www.crabhomes.com/product/1/4/Underwater_Island.html

ok so my bro was nice enough to order this underwater island for crabs. It is 12x10 and it is the largest one they have. It will be placed inside a 40 gallon tank. I have a few questions.
1. First can I mix rcc and fiddlers?
2. How many crabs can I get mixed or unmixed?
3 any one have or hear of the moon crab and what care they need?

[Spidyman]

http://www.youtube.com/watch?v=xRaFaJT3xEc&feature=youtube_gdata_player

[Lady Hobbs]

I enjoyed the video but I know nothing about crabs. I thought they were supposed to be in brackish tanks with sand bottoms tho. Maybe I need to read up on them more, huh? They are neat to watch.

[johndoe222]

Almost all aquarium crabs are brackish. And yes LH it is ideal for them to have a sandy substrate because there legs are designed to walk across sand.

[Spidyman]

Ya I have brackish and a sand bottom

[Rue]

Cool! I've never seen that before.

[Spidyman]

Ya it is new to the market and it allows you to easily keep not only Crabs but amphibian with fish