IMO, to much emphasis is being placed on water values here!!
Most fish you will find at your local fish shop will be able to survive quite happily in straight tap water with no manipulating the values!!
Although say Tanganyikans come from a ph as high as 9.0, this ph value is not needed to keep and even breed this fish (unless of course you are getting wild caught staright from the lake).
IMO you should not concern yourself with this as most fish available are already acclimated to survive in lower ph"s.
If, however you are planning on spawning fish, their are many who will need special ph values and then you would need to consider manipulating their ph!!
I have bred fish for over 10 years from all three African lakes with never altering the ph of my tap water.
I have also spawned SA/CA species without manipulating the ph.
In fact, I currently house a group of F1 firemouths in straight tap water and they are thriving.
This is of course just my opinion, but is based on the above mentioned 10 years of breeding experience.
You should concentrate more on a selection of fish that will live together in a certain harmony rather than worrying about the ph values of their native waters as they are probably so far removed from them it will not matter anyway!!
CM