According to Wikipedia "Fennario" is actually from a Scottish folk song originally called "The Bonnie Lass o' Fyvie-o". The song has an American name, which is "Fennario". Fyvie is actually the name of a place in Scotland.

The song was supposedly taken by Scottish immigrants to America, where over time the lyrics changed, as folk songs do, and "Fyvie" had to change to "Fennario" because the latter had three syllables and would fit the new lyrics.

In other versions the same thing happend to "Ythanside" (Scottish river) which changed to "Ethanside", and "Braes o' Gight" (Gight being a place) which changed to "braesogight".