Fiddler crab questions?

I think a 10 gallon or larger is find for tank size, I don't really know if they need companions. I think they will eat small fish, shrimp, bloodworms etc...and yes it should be filtered water and some heat as well. That's all I know about them. Check youtube that's where I go to look into information on fish. I was thinking about getting one and chose to get a dwarf frog to go with my fish instead.