After doing some online/book research on platies, I came up with an article that says that all livebearers (platies, mollies, guppies) need a little bit of salt in the tank water to thrive. They say 1 tea spoon per every 20 liters (about 5 gallons). Does anyone have experience on that? Does it really make a difference? Are there any potential risks in it? I also read that the salt should protect them from disease. I'm planning to start a livebearer tank, and am willing to make changes like add salt if it's considered useful for the fish.