I see what you mean. One of the clams died without me knowing. I went to pick it up, and BAM, the stench hit. That's NASTY.
I added new filters pads, Polyfilters, and some carbon to the power filter in the tank (in addition to the main filtration), so hopefully that will take care of the die-off. Thankfully I found it before it got too bad.
Anyway, Lou won't crack the clams himself. I have to crack them open and drop them back into the tank.