Fishtail Pave?

yes?

is fishtail only done in single lines?

Yes. Multiple lines are usually bead set. You would lose the beauty of fishtail in multiple lines.

I recall seeing one fishtail pave ring (single line) here on PS.

i saw an amazing ring recently that had a three line row of fishtail woven around the central stone. i wwas thinking that three lines of the fishtail (slightly domed) would be a beautiful band--wish i could find something similar pictured somewhere