| I can't see the thread you reference Ken. So, without that thread...I maybe
wrong here...but perhaps the luthier who did the work did not know what they
were doing??? Fish glue is well received in the restoration world. Also
lots of speculation in the violin world that fish glue was the choice by the
Italian masters.
Fish glue is strong...and expensive. The benefit over traditional hide glue
will be in the area of repair and restoration...namely gluing fresh cracks.
The glue, when fresh, dries nearly invisible. The strength should be about
equal to hide glue...perhaps stronger.
The good stuff is expensive and made of the membrane from the swim bladder
of the sturgeon, which is becoming scarce owing to over fishing for caviar
(thus the prices). It can be pretty stinky! I have found it from Dick and
Kremer.
I have been told by a Cremonese restorer that Japanese varieties are
completely odorless and far stronger than hide glue. Good for cracks, but
bad for things you want to come apart (like tops). I am unaware of sources
for the Japanese varieties.
Good luck. I would try it in a repair or restoration application, not new making. | 
Gulp Gulp... 
