Well, I kind of thought that freshwater and brackish water were pretty similiar but I am getting mixed confusions. The reason I need to know is for my ideas for my stock list for my 55 gallon tank when it gets set-up. I wanted to put silver-tipped sharks in the tank with a few other fish that I'm not really sure about other than with a school of Bala sharks. When the silver-tipped sharks are still babys, that isn't my concern because they thrive in freshwater during this period. It's when the silver-tipped sharks enter their adult age when they start to thrive in brackish water. To get brackish, I have to add a little salt, from what I understand. How much salt is one question? Another concern is, will this "Brackish" water affect the other fish in the tank? If it will affect certain fish, can someone give me a list of other fish that also thrive in salt water? Or maybe some advice from people that have owned silver-tipped sharks for a while would be nice or at least people who know about them. I appreciate all the help.