Ok I think I have a frickin Mantis in my 36glln tank. I have heard this "tapping" (like the thermometer is tapping the glass, AND YES I have made that isn't what it is!) sound. One cleaner shrimp, sniiped in half(clown fish fed it to her sea anenome before I could get it out!! Wen to go get the net came back and it was in the Sea Anenome!) the other one is MIA!!!
I also have a tiger shrimp in there, do you all think it can handle it's own?