Cook pasta according to package directions. Drain, reserving 1/4 cup of the cooking water. Set pasta and water aside. Meanwhile, season fish with salt and pepper. In a very large skillet heat 1 tablespoon oil over medium-high heat. Add tilapia. Cook about 6 minutes or until fish flakes easily when tested with a fork. Remove fish and set aside.
Add remaining 1 tablespoon oil to skillet. Add onion and fennel. Cook and stir for 5 minutes or until tender. Stir in garlic, capers, and Italian seasoning; cook and stir 1 minute more. Stir in undrained tomatoes, tomato sauce, and reserved pasta water. Bring to boiling. Boil gently, uncovered, for 8 minutes, stirring occasionally. Remove from heat. Stir in the pasta and fish, stirring to break up fish slightly. Sprinkle with parsley.