This is a very common food fish here in Germany. There are several recipes available for cooking this fish. It’s grouped with a few other species called “Plattfisch” (flat fish), because of the special anatomy.
These fish come out of their eggs with one eye on each side of the head. But, as they grow older, one eye starts moving to the other side of the head and the fish starts swimming with the side without an eye to the ground, while the side with both eyes is turned up. This way, the fish can hide easily in the sand and observe the water above him.
I took that image of the not completely full-grown plaice in an aquarium.