Aquarium Salt for Fresh Water tank

Question
Hi -
I was just at the pet store to get some new fish for a recently re-established fresh water tank when I saw "requires aquarium salt" on the labels for fresh water fish like mollies, platies etc.  I have never seen this before and know I had problems in the past with these types of fish.  I got some and added it to the tank per the instructions.  The fish are doing great!  I am just curious what this is and how often should I add aquarium salt to the water? I also have a betta, gouramis, catfish, zebras & a pleco in the 30 gal tank.  
Thanks for your help!
Julie

Answer
Hi Julie,
Many sources recommend aquarium salt for livebearing and some other groups of fish... Salt is good and some livebearers do need it-particularly wild caught mollies and the like. But there are many aquarists whom keep livebearers without aquarium salt...and their fish do just as well. It all depends on your choices and preferances. I really don't use salt but only as for treating very stressed fish, infections, or injuries. But otherwise, just good clean warm water is provided for all my fish and they do wonderful. Salt is a good prevenative for some parasites or diseases and what it all comes down to I guess is this-- if you see your fishes behavior and well-being greatly improved by the salt. Go ahead and use it! That's fine.
~Be careful with using salt with your catfish. You didn't mention what species you keep but many are intolerant to salt because of their sensitive sometimes scaleless skin in some species. Just be careful.

Salt is a one time addition. When water evaporates, just the water leaves and the salt (plus other minerals) are left behind so you should remember to only add pure fresh water when topping off your evaporation. When making water changes, just add the proper amount back according to how many gallons you changed out and added.

I hope this helps! Remember to only use rock or aquarium salt. Table salt is harmful because of the additives...don't ever use it.

Feel free to write with anymore questions or concerns you may have...

Best wishes and happy fishkeeping!
Karen~