Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente.

While the pasta cooks, heat the olive oil in a large skillet over medium heat.

Add the sliced garlic and red pepper flakes to the skillet. Sauté for about 1 minute until fragrant, being careful not to burn the garlic.

Pour in the canned pilchards (including the tomato sauce from the tin) and the diced tomatoes. Use a wooden spoon to break the fish into bite-sized chunks.

Stir in the chopped olives and capers. Let the sauce simmer for 5 to 7 minutes to thicken slightly and allow flavors to meld.

Drain the pasta, reserving about 1/4 cup of the starchy cooking water.

Add the drained pasta to the skillet with the sauce. Toss well to coat, adding a splash of the reserved cooking water if the sauce is too thick.

Remove from heat, stir in the lemon zest and fresh parsley, and serve immediately.