You can replace the coregone with another lake or sea fish with a delicate flavour, not too intense.
The pleasantness of this dish lies a lot in the freshness of the ingredients, both of the fish and the vegetables, collected in the garden just before being cooked. The choice of olives and extra virgin olive oil, both of great quality, is also of great importance.
You choose which vegetables to use, it is important that they are in season and fresh.