I'm not too horrified as I have had this tank up since right after Christmas and after I placed in the rock I had been doing a lot of studying on the subject of mantis shrimp.
In my case the rock was Keys and Live Base Rock from liverocks.com. It is absolutely beautiful. I added another 30lbs of base rock from hirocks.com and I cycled with a shrimp.
All this time I was aquascaping, testing water and searching for the pistols or mantis. I did find one tiny mantis in one of the bags the rock was in so I knew there likely could be more. He was very small though. I never saw any pistols but half hoped that was the 'clicker' in the tank.
Yesterday I brought two healthy clowns home and they are quite happy thus far. But last night as I'm watching, there it is, first time I've seen him, a mantis on the sand at the base of a rock in a little burrow ! I'll get him. I'm not going to lose sleep over him just yet. I picked up two crabs from my rock and he hasn't gotten them yet. The clowns swim high and so they aren't near the entrance to the little killer's burrow.
The trap method I'm going to stick with is the water bottle with top cut and placed in backward. I'm going to bait him with a wafer in the bottle and place it near his burrow. When I first set the tank up I tried this but I didn't know where to place the trap. Now that I've seen him (and I'm hoping he hasn't moved, I have read they are smart devlish buggers) I'm going to place the trap very near his burrow.
I'm hoping if he gets anyone he gets one of my crabs
When I saw him last night I could not tell if his appendage was that of a spear or smasher. The way I identified him was his eyes. Nothing like those high set praying mantis like eyes.
It was so odd. I'm kneeling looking in and thinking, is that a mantis ? and then he backed in his burrow. I then took the flashlight and shined in and sure enough, it is a mantis. he backing up further in so I suppose my one problem now may be that he moves on and I have to find him again.
I don't get the feeling he ventures out often if ever. Not sure how he is surviving but I get the feeling he stays in the rock all the time. If I have to I'll pull the base rock this burrow is under. :-(
I read an article in a San Francisco newspaper about how mantis plague the public aquariums out there. We need a natural predator other than the trigger.
By the way, the clowns are everything I hoped for. The camraderie between the two is really cool. I'm liking the clowns big time.