Why are all of my clams dying???

[Borderjumper]

I'm going thru exactly the same thing.. I've lost four so far. The clam will appear fine and happy one day, then the next morning the shell is gapped so far open it's tearing the syphon hole. then dead that evening. I would think that if it were a disease or a pathogen that they would all die at once.. Not one every 4 days or so. A few have been in my tank for years. I bought new clams last month.. Lost one new one and three established ones.. I moved the remaining three to my frag tank to see if they do better in there.

I've noticed my cleaner shrimp around them lately, maybe they are eating them at night from the bottom?? I just have no clue. like you, water is good and everything else is ok.. 3 tangs in the tank, a regal,yellow, and naso. the mantels don't look picked on.. They just spread apart at the hinge.