My newest 135 has been up and running for a year since the last addition of live rock. At about three months I caught and removed 3 mantis to the LFS. The popping sound of a shrimp has never stopped an tonight I saw first hand why. I added frozen formula one cube to the tank which sank before the fish could consume. I noticed the cube being dragged under a rock and watched expecting to see the resident rock crab. What I saw was the resident rock crab being held at bay by being popped in the head repeatedly by a 3" brown mantis. I have six fish in the tank and numerous crabs, snails and two shrimp and have not noticed any casualties in months so I was surprised.