I've had to get rid of 3 mantis shrimp in a 2 yr period or so. They seemed to be very common in the live rock i was getting.
I read one way to get rid of them is to pour soda water? i think soda water. Just water with CO2 carbonation in it. They come sho0ting out of their holes b/c they cant breathe. Problem is, you kill everything else similiar to him, sucks.
They make traps, just nothing more than a littel box witha spring loaded trap do0r and you bait it with a piece of fo0d.
Either way, they suck. Will destroy the inside of your LR and kill other inverts, possibly fish. Some people like to keep them in a tank by themselves. The peacock ones can be quite pretty, but they always have a serious negative attitude. Saw one at a LFS that was about 8 inches long, was real co0l lo0kin.
Then again, I read a story about a guy that was messin with one in the wild, and it ended up with him losing his thumb.