Place a pizza stone or steel on the upper-middle rack and heat the oven to 260°C (500°F) for at least 30 minutes. If using a baking sheet, heat it in the oven for the last 10 minutes.
Take the dough out of the refrigerator an hour before, if chilled, until it feels soft and stretches without snapping back.
Press the tuna between paper towels to remove surface oil. Flake it into large chunks and set aside.
Shave the fennel with a mandoline or very sharp knife into slices about 1/16 inch (1.5mm) thick. Toss with 1 teaspoon olive oil and a pinch of salt.
On a floured surface, stretch the dough by hand into a 12-inch (30cm) round, working from the center out and leaving a slightly thicker rim. Transfer to a floured peel or parchment.
Spread the sauce thinly, leaving a 3/4-inch (2cm) edge. Scatter the mozzarella, then the fennel, tuna, olives, and lemon zest.
Slide the pizza onto the hot surface. Bake for 8 to 10 minutes, until the rim is deep golden with dark spots, the cheese is bubbling and lightly browned, and the underside is firm and speckled when lifted with a spatula.
Transfer to a rack for 2 minutes, then top with Parmesan, fennel fronds, remaining oil, and black pepper. Slice and serve warm.