Oh oh - fish MIA!
 

Hi - it's me again with a new problem. Over the past few weeks I have fish disappearing - not a trace! MIA: bicolour psudochromus, scooter blenny, christmas wrasse, 2 cleaner shrimp and now I can't locate the bi-colour blenny! They haven't jumped out, no dead bodies, can't possibly hide that long - 50 gal tank. So, do I have an evil, unseen predator? Remaining fish are coral beauty, mandarin goby, yellowheaded sleeper goby, 2 cleaner shrimp. Have assorted corals: fox, candy cane, colt, various zoos, various xenias, various mushrooms, sun coral, coco worm, feather dusters, snails, & 1 small emerald crab which I haven't seen for a while. I have heard several loud snapping noises . . . could it be that there is a mantis shrimp in the tank? I've never seen anything like that at any time of the day or night, but I know they can hide well. Any suggestions would be welcome.

Bust out the flashlight with a red cover and watch.

Is it rapid, consecutive snapping or snap, pause, snap?

If it is rapid snapping, then it is most likely a mantis. If not, then its most likely a Pistol Shrimp.

Yikes!
 

Definitely snap, pause, snap . . . so if it's a pistol shrimp, should I remove one rock at a time until I find him? I thought this was the shrimp that chums around with the shrimp goby, or am I confused?

That may be a pistol but not 100% guaranteed. If it is a pistol shrimp, they usually won't go after fish...

Another possiblility is there's a huge hitchhiker crab in your tank...

Yup!
 

Must be something! Oh yay - another tank tear-down! :rolleyes:

Trap it
 

Well I'm all for the night stake out and look for a predator coming out at night...even setup a small trap in the tank with some food in it. Maybe the buggar will go in the trap to get some easy food...and wham...you've got him.

Best to find out which rock area it likes to reside in too...might save you from tearing the entire tank apart and stressing out your survivors.

Yup . . .
 

I like the stake-out better too . . . the corals have grown onto neighbouring rocks, they would'nt be happy! I'll put a trap together this weekend - should be able to get him. I know he's in the back corner, I should be able to get pretty close!