pH is just a number, fish don't really "feel" pH. What's most important is TDS, total dissolved solids - but a TDS meter can be expensive.
Not true as xtreme pH can effect eyes, slime production, etc.
So the next best thing is to look at your alkalinity (KH) and general hardness (GH). What are your values for these levels - tap water and tank?:iagree:
Also, are you using a liquid test kit? These are better than strip, by far.:iagree:
In short, buffering has more to do with KH than pH. Don't fixate on pH too much. Find out what the shop keeper is keeping the fish at where you're getting them from, for starters, and go from there.
KH affect stability of pH and they all affects one another one way or another.
As Bob mentioned, all of the fish you are planning to keep, if not wild caught, are farmed and able to adapt to more than just the narrow range of water chemistry you may find as the "recommended" ideals.