Should you add salt to fresh water tank?

No, you should not add salt or other chemicals to your freshwater tank. Adding any type of salt to a freshwater tank can raise the pH level past a level that is suitable for most freshwater species. Many tropical freshwater species of fish and plants can only tolerate a pH range of 6.0 to 8.0. Fish and plants can become distressed and potentially die if the water becomes too basic.

Salt may be used as medication to treat fish ailments, but this should be done only in a separate hospital tank and carefully following the directions of an experienced aquarist or veterinarian.