I have always found that if you think it is starting to deteriorate then it's days are numbered. I have never had a clam "get well" I have had clams get stung ..last one was from a mushroom.... But usually the culprit is too much water flow. My last clam passed because of too much water flow. It was from a power head on the other side of the six foot tank. And not even having it's water flow towards the clam. Live and learn.