Crab with live reef?

[micah creekmore]

So I've got a 46 gallon tank we are moving into our new home. I've emptied it out of fish except for 1 damsel and 1 crab. It's not a red legged crab or blue crab...just the normal fairly ugly crab. Not sure the official name?
What I'd like to do is to keep them both alive (my 3 year old loves that ugly crab). I have a 24 gallon nano reef tank. My question...

Will the crab eat the corals in the reef tank?

Also...if I put the water from my 46 gallon tank into 5 gallon containers....will it keep and be safe to use (with the live bacteria) in a few weeks? Or should I just plan on adding new water?

 

[bang guy]

Surprisingly there is very little bacteria in the water so it serves no purpose to store it. Just start with new water.

Crabs don't generally eat coral. If it can catch your fish it might eat that but not the coral.