I had one in my tank until about 2 weeks ago. He caused absolute carnage in my tank and would stack the shells of his kills right at the front of my tank
He also took out a few gobies and peppermint shrimp during his reign of terror. I set up a few traps with no luck and the only way I caught him is I found the rock he made his home in and pulled it out when I saw him in it and now hes living in my sump.