Nope. The beneficial bacteria that allow aquariums to function are, by and large, not free swimming in the water column. This is why moving water from an established tank to a new one has little if any effect. The water from a creek increases the potential for disease or parasites to be imported, and without knowing the full story of the water upstream, potential contaminants (heavy metals, salinity, etc). There's no such thing as 'balanced' water. Waters will vary in terms of chemical composition, ranigng from high to low pH, KH, and GH--may be appropriate for your choice of fish, may not work, but the same can be said of tapwater. At least with tapwater you know that you aren't importing giardea to your home.
