pistol or mantis shrimp ?'s

I have a question I have heard a clicking noise coming from my tank the last couple of weeks that i have noticed. I have done a lot or research on pistol and mantis shrimp and this sounds like what i have in my tank. The only problem i have as i never seen the little bugger nor can i find his home. I have 10+ missing fish that have been there one day and gone the next. Anybody have any advice on how to catch and find these that they have had luck with?
The net doesn't have very much information on this.

Im pretty sure you can make a pest trap for him, they are similar to fish traps just smaller opening.

You can try the old inverted pop bottle with food inside and a rock in there to hold it to the bottom. Tie some fishing line around it so you can yank it out quick and check after lights are out for awhile.