Setting traps for crabs

[marcingo]

I'm pretty new to reef keeping and this site has been invaluable teaching me so much. Would like to thank everyone.

I set up my 10 gallon nano 2 months ago with a bunch of live rock. About a week ago I bought 9 more pounds of live rock from someone's personal tank and I have now noticed a black and white striped crab in the rock. I've only seen him maybe twice since hes always hiding. Now I know crabs are bad things to have in a reef so I'm wondering what would be the best way to trap him and get him out of the tank. I heard lots of people put food in a glass and hope to catch the crabs at night. Is there any other effective method any of you guys have used?

Thanks again.