In Danusia Stok's translation, the list of strange fish is one monster short. The original quote in Polish does not say "fishermen bring him the oddest fish — octopedes, clabaters or herrongs", but rather "fishermen bring him dziworyby, octopedes, clabaters or herrongs". The name for "dziworyba" is not translated into English.
To be fair, "dziworyba" does roughly translate to "odd" or "weird" fish, but in the original Polish text, it is listed as an instance of a creature, not a catch-all expression.
In German folkore, there is sea creature, a kind of water sprite, known as a Klabautermann. It's possible the reference comes from this tale.