It turns out that there is a very cute lower bound on the skewness g_1 of a strictly positive set of data having given mean and sd:
For reasons outlined in this PubPeer post, I have to suppose this is a very old result. But the authors claim to have done a diligent literature search, and I have no reason to doubt them.
So I’m wondering if a citation might come to mind for any of you who read Fisher’s writings over breakfast in the original Sanskrit — lookin’ at you, @Stephen @R_cubed and @Sander!