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that claims that, in general, it is a myth that mollies will thrive better in a brackish tank as opposed to a freshwater one.
I've been planning on setting up a brackish tank just for mollies because my mollies keep dying and I don't know why. I regularly test for ammonia, nitrites, nitrates, and pH and they are all within acceptable parameters. Water temperature is also in the 78 to 80 degree F range. The only thing I can think of is either a) bad stock (I do get all of my fish from the local Pets Mart), or b) wrong environment. Since I've been reading everywhere (not just here) that mollies are really brackish fish, I figured that it's possible that the reason why my mollies keep dying is because I got them in the wrong kind of tank. Then I come across this article leaving me totally confused.
The article does indicate that it's not the saltiness that matters; it's the hardness. I've never tested the hardness of my water. I'll goto the LFS to get the right testing kits today after work. Maybe it's been the water hardness all this time?
My water is liquid rock and I still couldn't keep mollies alive for 2-3 years until I switched to brackish. Why not set your brackish tank up and see for yourself, or at least just add the marine salt to the tank they are in (if they are alone now) and watch their reaction. You won't doubt they love salt after you see their reaction while you are adding it.
They are routinely collected from the wild in both brackish and even full salt water...maybe the fish didn't read that article either? "The only ones among you who will be really happy are those who will have sought and found how to serve." --- Albert Schweitzer