Cook the pasta in a large saucepan of salted boiling water according to the pack instructions until al dente.
Meanwhile, mix together the garlic, lemon juice and rind and olive oil in a bowl. Using a fork, break the tuna into large chunks and carefully stir into the dressing with the capers.
Drain the pasta, reserving a little of the cooking water, and return to the pan. Stir through the tuna and dressing, adding a little cooking water to loosen if needed. Season well, then stir in the parsley and serve immediately.