Planted Tank Enthusiast
Join Date: Nov 2006
Location: Calgary, Canada
Guess you have to clarify what you mean by salinity, if you mean water hardness, it is generally preferred that the water is softer. However, not all plants and fish prefer soft water, african cichlids and valisneria come to mind as obvious exceptions.
You might also mean electrical conductivity of the water (that's what I think of). Again, different plants will respond differently as will fish.
What kinds of plants and fish do you want to maintain?