Grate 1 tablespoon of zest from the second lemon, then squeeze the juice.
Combine the grated zest, breadcrumbs, salt and pepper in a small bowl and stir to mix; set aside.
Lay the lemon slices in the bottom of a baking dish.
Put the lemon juice in a shallow dish.
Dip the fish pieces in the lemon juice and set them on the lemon slices in the baking dish.
Sprinkle the breadcrumb mixture evenly over the fish pieces and bake in the preheated oven until the crumbs are lightly browned and the fish is just opaque through, 10 to 15 minutes (depending on the thickness of the fish).
Transfer the fish to individual plates with a few slices of lemon for garnish; spoon some of the cooking juices over and serve immediately.