Dealing with a predator in a reef
 

Not too sure exactly how I should deal with this as I'm somewhat new to marine tank keeping, (with in the last year and a half.) I've recently lost 3 fish, Mandarin dragonet, Lawnmower blenny, and now my Firefish. I'm pretty sure it's a predator of some sort as I have been hearing a clicking in my tank, usually after the lights go out. I have a 46 bow with about 60lbs of rock. I also have a 55 fowlr with a Dragon wrasse, Picasso trigger, Valentini all about 2-2 1/2". I also just got a 5" Niger trigger from a bud. Yes I know the 55 is too small as these fish are going to get big and I plan on upgrading. The Niger was in a 33 but thats a whole other story, and I figure I'm doing him a favour by giving him an extra foot of swimming room for now. Anyhow I'm wondering if I removed the rock work from my reef, as I'm unable to pin point which rock this predator may be in, and placed it in my fowlr, would my predators do the work on the predator living in my reef rock? I do know by doing so I will more than likely lose all my brittle stars, speghetti worms, etc. but I'm willing to do this in order to save my fish. Thanks for your time.

dragon wrasse would be my first guess, clicking is probably a pistol shrimp and even if its a mantis fish are not usually the fist thing to go missing

the dragon wrasse is in a different tank - that's my understanding anyways.

Yes the dragon wrasse is in the fowlr. The missing fish are from the reef. Something in there is murdering my fish. They have all been fine in my reef for the last year or so. Side note, my firefish must have decided to "sleep in." Couldn't find him this morning and he wasn't in his home when I looked. But 2 fish in a month plus one fireshrimp and one cleaner also MIA tells me that something unfriendly is in there. Just wanna know if I transferred rock to my triggers if they would take care of whatever it may be?

That depends on what it is.
You might want to try trapping it. Mantis Shrimp and larger predatory crabs can both be trapped.

Well...my opinion is that it is unlikely that your fish are being killed by a crab or mantis. Probably just a run of bad luck or something not optimum about the tank.

How long have you had these fish? (The one's that didn't make it)

I had the lawnmower for about 1 1/2 years and the dragonet was about 1 yr. Got it super skinny and it was thriving in my tank. Getting very fat. I have a huge pod population. They were both very healthy. Reason why I think someting is preying on them is that I've been hearing a clicking sound lately and louder then hermit or snail shells on the glass. 3-4 clicks, pause, 3-4 more. Seems to be the back of the tank where it comes from and I cannot really see back there as I have a fair bit of rock in there. All water peramiters are within reason. Regular water changes. But like I said I'm still kinda new to the hobby so I'm open to suggestions and input. I've also been thinking of aquascaping both tanks again so thats why I ask if my predators will take care of a murderous crab or shrimp.

I've had a Pistol Shrimp in my FOWLR for over 2 years now. I have/had a Pink Tail Trigger, Blue Chin Trigger, Niger Trigger, Humuhumu Trigger, Blue Ring Angel, Bursa Trigger (RIP), and Clown Trigger (RIP). The Pistol is still there. If it's a crab you have...maybe. But then, how will you know when they've dealt with it?

Good question. Never thought of that and that is why I'm here asking you all for some input. I just assumed that triggers, wrasse, and puffers enjoyed shrimp/crab dinners as much as I do.

Regarding my Pistol....I'm sure my Triggers would enjoy chowing down on it....if they could get it. In other words, I think Pistols are more elusive than crabs. That's why I say "maybe" to crabs. I have a hunch my FOWLR is crab free. Not sure. It's been awhile since I looked at the tank at night with a flashlight.