Snapping sounds in my tank
 

I just added about 80 lbs of live rock to my tank and now once in a while I hear snapping sounds comming from my tank. They seem to come in fast groups of 3 , I had a mantis shrimp hitch hiker from some other rock but I got rid of it. I have a fidler crab, could he be making the noises. I have lost 3 fish since I put in the new rock. I have a very small crab which I believe is a gorrila crab living in one of the rocks, but it seems to small to be killing my fish. Any body know what makes a loud sharp snapping sound ???

I think you might have another mantis in there somwhere

or pistol shrimp

Just the missing fish leads me to think mantis....not sure but i dont think pistolshrimp will kill fish

the other mantis didn't make any sounds like I hear now, could either of the crabs be doing it ? I heard that gorrila crabs are bad ???

The snapping is rapid fire if that means anything ??

I don't think you can tell the difference between a pistol or a mantis just by the snap noise. I wouldn't worry about it either way.

I am pretty sure the fish are worried about it

There are a number of things it could be. Mantis and pistol shrimps get blamed most of the time. But I've heard similar noises from clown fish that will making a snapping sound with their jaws from time to time. Additionally, I discovered earlier this year that blue leg hermit crabs can make similar sounds as they attempt to violate each other for their shells. I was sitting by my tank and heard that dreaded clicking sound and jumped up to see what it was. I discovered it was a hermit crab violently tugging on another crab trying to evict it from its home and hitting the shell on the glass of my bare bottom tank.

maybe check out some cheap diy mantis and crab traps just in case, leaning a glass jar with bait on the bottom against a rock for the night might catch the gorilla before it causes any (more?) damage, also i had a HH pistol shrimp, he would snap sometimes several times (up to 5 or 6) about a second apart but never caused any problems, only ever saw it twice just heard it lots