If you Google "I never will marry" the first hit is a lovely video of Johnny Cash and Linda Ronstadt singing that song on Cash's old TV show. They both were in top vocal form that day. But what is really interesting is, instead of "the fish in deep water swim over my head" Cash sang, "the rushing deep waters will molder my head." Kind of grisly, eh? But since Cash was married to June Carter, I have to assume that those are the words she learned as a child from Maybelle or A.P.
Even though when the Carters recorded it I believe they used the fish verse. I wonder if "John Brown's Body" is the only well-known song to use the word "molder" or "moulder" in the sense of decomposing?