Betta with a red claw crab?

Question

I stopped by the pet store looking or a 5 and a half gallon tank for my betta. While I was there I also wanted to get a ghost shrimp to act as a scavenger. Instead, the salesman told me a little red claw crab will have a better chance of surviving. So I got one. So far the two are living happily together, the betta spends most of the time above and the crab, when not climbing on the artificial plants, will hang around on the bottom.
My questions are:
-is it true that red claw crab actually like a bit of salt in the aquarium? If yes, what would be the best compromise, as I do not want it to negatively affect the betta
-if I don't think he is getting enough food from scavenging, can I drop maybe a pea in there? What food pellets would you recommend?
-does he absolutely need something to climb onto and hang on the surface?
Here is a picture of my set-up.
http://img70.imageshack.us/img70/4094/1006575sg9.jpg

Thanks everyone!

Answer 1

This site might be able to answer some of your questions?
http://www.bettatalk.com/basic_care.htm

Answer 2

I have had Betas, crabs and frogs in various habitats and combinations over 22 years. Betas like to be alone the best. I once put my Beta in with four small goldfish in a 29 gal aquarium. It worked for awhile but there was to much current in the tank for the beta. Betas don't seem to like moving water, Moving anything for that matter. I tried getting a frog to keep the Beta company for a while. Nope. Beta started to eat the frogs toes and keep him from getting enough air by guard the surface. Now they are in separate bowls next to each other on a stand. Crabs can be very out-going and persistent. I've had crabs in with fancy gold fish (very bad), regular goldfish (bad), beta (not good either). My Betas have tended to stay near the top of the bowl. But since the crab likes (needs) to be out of the water at times he will climb up there and he will find a way to snack on Beta fins. Crabs can be very patient. If you want a pretty Beta and a happy frog and a happy crab don't put them together. Together they will eventually pick each other apart. You'll end up with a fat crab.

Answer 3

Red claw crabs are brackishwater and need to be able to breath air to live. So there is no way it can survive with a betta.

http://badmanstropicalfish.com/profiles/profile101.html

Your best chance is ghost shrimp. Just start out with 1 though, your betta may or may not eat them. It seems about half of bettas will eat them, half won't so go ahead and try one and if it does get eaten, you only waste a quarter.