Originally posted by Birdy
If you can see which rock he has made his home in, then pull it out of the tank and squirt the rock with selzer water, and it should come out. Make sure it is a mantis shrimp and not a harmless pistol shrimp.
IMEo, this is by far the best adn most assured method, if you know which hole he is hiding in, do this. If not, try the trap. Other methods work only at times. But this one has never failed anyone that I have talked with. Just be careful not to stick your fingers near his hole!
as far as will it.......... well, that depends. Most do not actually break the tank, whowever most do hunt and will go after fish. It is really up to the individual mantis whether or not he wil do damage. Feeding him may help alleviate any possible problems, but it is NOT guarenteed.