They sell a Fish Glue described as : liquid very strong
great for veneer repair.
Also a "Isinglass Glue" Russian Sturgeon Glue.
This may be of interest. It comes from a book describing
various glues and gelatins:
Isinglass is a nearly pure collagen. When soaked
in cold water it swells greatly without losing its
organized, fibrous, thread-like structure. Boiling
converts it into gelatin which, probably because of the
ease of its formation, yields a very strong jelly.
When treated with hot water, Russian isinglass
dissolves completely, swelling uniformly to produce a
whitish opaline jelly. This distinguishes it from
gelatin, which swells irregularly in hot water, giving
in most cases a more transparent solution.