My encounter with Günter Grass' Flounder in the Ulica Mariacka (Mariengasse), Gdansk.
Meiner war und ist ein sogenannter Steinbutt ...
(Der Butt, S. 33-34)
More on the Steinbutt
The Psetta maxima or European Turbot (Steinbutt in German) has both eyes on the left side. The European Flounder (Platichthys flesus) however, has both eyes on its right side, as has Grass' etching on the book cover...
The stone relief in Gdansk is definitely a Turbot, not a flounder.