Cook refrigerated fettuccine according to package directions, omitting salt and fat. Drain and keep warm.
Heat oil in large nonstick skillet over medium-high heat. Add garlic to pan; cook 1 minute. Add flour to pan; cook 30 seconds, stirring constantly with a whisk. Stir in herbes de Provence, turmeric, tomatoes, and clam juice; bring to a boil. Stir in mussels, shrimp, and fish. Cover, reduce heat, and simmer 5 minutes or until mussels open. Discard any unopened shells.
Place 1 cup pasta in each of 4 bowls; top each serving with about 1/3 cup fish mixture and 3 mussels. Garnish with basil, if desired.