Hi red,
GH is not something we take action on but is nice to know. KH on the other hand is very useful. Your KH of 7 is quite good in the sense that it is high enough to buffer your water nicely and keep you from having pH "swings" (too rapid changes of value) very easily.
So your KH will be helping your pH to hold and pH is generally what will be noted for preferences of particular species. These noted preferences usually refer mostly to what it is observed that they experience and like in the wild, so specimens that are raised in captivity may be less sensitive to this (and whether they are wild or captive is something you usually won't be able to know.) Always keep in mind that not having large or rapid -changes- in pH is much more important than the -actual- pH except for a few specific species where it is generally accepted that pH is more important.
Once you are interested in a particular species, you can ask the experts in that particular forum about their experiences of whether pH is a big deal for your choice.
Hope this helps,
~~waterdrop~~
