Cook pasta according to package directions in salted water; reserve 2 TBSP cooking water. Drain pasta and return to pot.
In large skillet, heat oil over medium heat. Add garlic; cook until fragrant (1 minute). Stir in tomatoes, salt, crushed red pepper, and sage. Cook over medium-high heat, stirring and pressing down occasionally, until juicy (5 minutes). Stir in tuna and zucchini. Cook 5 minutes. Toss with pasta and reserved cooking water. Sprinkle with Parmesan.
