You're most welcome. I've no idea how long it might take before the average molly would begin to succumb to soft and/or acidic water, I can only say it will. The common "shimmy" is often one result, and another is fungus; generally, the fish is more prone to disease than it otherwise should be. Any stress weakens a fish, and some other issue that would ordinarily not be critical may become so, and cause the demise of the fish. Without microscopic examination via autopsy [I believe there is a word for this as applied to fish, just can't remember it, but you will know what I'm saying] of the deceased fish, it is impossible for any of us to ascertain the cause of death. But we can say with confidence that all of this is linked, and eventual problems are usually traceable back to issues.
It is also noteworthy that the years of inbreeding commercially have significantly weakened this species, something that applies to all the livebearers and many of the "bread and butter" fish too.
Mollies are also especially sensitive to ammonia, much more than many other fish, so new tanks (until fully cycled and then established), overcrowding, overfeeding, or slack maintenance (water changes) can quickly cause real trouble.
Byron.
It is also noteworthy that the years of inbreeding commercially have significantly weakened this species, something that applies to all the livebearers and many of the "bread and butter" fish too.
Mollies are also especially sensitive to ammonia, much more than many other fish, so new tanks (until fully cycled and then established), overcrowding, overfeeding, or slack maintenance (water changes) can quickly cause real trouble.
Byron.