Yea they will also lay their eggs on the bottom side of some SPS causing tissue recession which; if a large enough colony of eggs, can really hurt the coral. Mine is in my 29 because I probably couldn't find him in one of my 125's. I have softies and a couple of LPS and thats it. He really likes anything thats green, aka my polyps, green shrooms, and frogspawn. He enjoys blending in lol. He's a funny little guy to set and watch.
My Purple Firefish in my 29 is named 'Goby One Kenobi' hence the whole star wars theme.
Edit: Just be sure not to buy anything from AQUACON.......The name says it all. I've heard horror stories about this company. There is a reason they have nice pictures; it makes up for their service.