J.S. Bach did not write tuba sonatas. I’m sure he would have, but the instrument didn’t even appear until the mid 19th-century.
I’ve known several great tuba players over the years and, for some reason, they seem infatuated with the flute repertoire. (I think they just like to show off!)
When I chanced upon this recording of tubist, Alexander Lapins, performing Bach’s Flute Sonata in E-Flat Major, I couldn’t resist sharing it here.