I personally would not be concerned with GH at all, unless for some reason you've got extremely hard water. I think it is much more important to prevent swings in hardness and osmotic shock, which ironically can sometimes occur when someone is trying "correct" GH!
I couldn't find any GH info but there are reported
stream measurements for laoensis indicating that the pH of their stream habitat ranges from 5-6. As mentioned, pH is not a measure of GH, but these relatively low pH values are certainly consistent with a low GH.