Mantis Shrimp!
 

Looking in my tank today and I see clouds of sand coming out of a hole in the live rock. I go over and there he is, staring at me with his smashers out. He is a small guy, less then an inch. I have corals, anenomes, and a bunch of large fish in a 110 gal, is he dangerous? Or should I keep him around?

Maybe get another mantis and watch them battle...? j/k

he shouldn't be dangerous to your fish, but he may cause troubles with your rock work by tunneling they move corals and things too for their burrows. Not to mention smaller hermits and snails will become food. What color is it?

Come by my place this Saturday and see if you can locate one of the five or six that I have in my tank. If it is as small as you say, I don't think it will cause any serious problem for you.

...but it has to eat something to survive. You can hand feed it, or you can leave it to hunt hermits. Both ways are entertaining.

Brad

at an inch long the only thing in danger would be small snails like nassarius. poses little threat to fish larger than itself and almost none to corals. if you have frags that are smaller than it, you may want to glue them down.

chances are, in a 110, you will very rarely see it.

I see it all the time... he comes to the entrance of his neat little burrow in the live rock and just chills there.