Thaw fish and shrimp, if frozen. Rinse fish and shrimp; pat dry. Cut the fish into 1-inch pieces. Cover and chill fish pieces and shrimp until needed.
In a large saucepan heat olive oil over medium-high heat. Cook and stir onion, carrot, sweet pepper, and garlic in hot oil until tender. Stir in the undrained tomatoes, tomato sauce, chicken broth, wine or chicken broth, bay leaves, dried thyme (if using), Cajun seasoning, cumin, and if desired, crushed red pepper. Bring the mixture to boiling; reduce heat. Simmer, covered, for 20 minutes.
Gently stir in the fish pieces, shrimp, and fresh thyme (if using). Cover and simmer about 5 minutes more or until the fish flakes easily when tested with a fork and shrimp are opaque. Remove the bay leaves before serving.