Such small hunting sabers, in German called Jagdplaute, are relatively common in Germany. So I would guess that your piece is German, too. Often they have a bird on the guard, a fish is far more rare.
The attached picture shows some similar pieces, dated to the mid 18th century. It is from this side:
http://myarmoury.com/talk/viewtopic.1457.html
So maybe I was wrong at first and your piece is a half century older than I thought.
Regards
Robin