how to set up fiddler crab

My sons are all of a sudden very interested in fiddler crab. I need help before I make purchases.
which one is better: all sand or all gravel set up? sloping with water on one side of the tank?
if it is gravel, do I need a air pump filter set up?
should I add salt to my own tank after I purchase the crab from the store?
does the crab really eat everything> or do I have to feed shrimp and loster bites?
Thank you in advance for your time.

 

O.k just google fiddlers tons o links as for the food they will need to eat crab and lobster bites and as adults they will eat small ghost shrimp or brine shrimp there will need to be a filter and an acess to land.

 

sorry, I do not quite understand what you mean by "google tons o links:
it sounds like to the end of your comment that they need a filter. Is that the one that is flat, you put it in the bottom of the tank, and then place the gravel on top?

 

He means use the google search engine to look for "Fiddler crab".

Stay away from undergravel filters if you can.