yes, mollies live in mostly brackish conditions in the wild. A majority of their lives are actually spent in mostly saltwater environments. They do move upstream into freshwater environments to breed like many types of fish such as salmonids, although they can successfully breed in saltwater since they are livebearers, and their young are tiny miniatures of the parents. Platy's however, much less is known about their life cycles. My first experiment with a 24 hour slow drip acclimation to saltwater was unfortunately a failure. The test subject (a red wag platy) showed signs of distress within 12 hours of drip acclimation, and was removed safely from the experiment. Within a few hours of being re-acclimated to freshwater, the subject expelled its egg clutch, which presumably may have been the cause of the distress. It also may have been brought on by the salt. Further tests would be needed to create a hypothesis on this. Test subject #2 is a male, to eliminate pregnancy as a factor in this experiment, and has been slow drip acclimating now for 12 hours, and shows no signs of distress yet. It will be watched closely for any signs of distress, and removed to be slowly re-acclimated to freshwater if any sign of stress is seen. I will update with my further findings on this test.