If frozen, thaw fish and shrimp. Pat dry with paper towels. Cut fish into bite size pieces. Cover and chill until needed.
In a 3 1/2 or 4 quart slow cooker, combine undrained tomatoes, water, sweet pepper, wine, onion, garlic, Italian seasoning, and salt.
Cover and cook on low heat setting for 4 to 5 hours or on high heat setting for 2 to 2 1/2 hours.
If using low heat setting, turn to high heat setting. Add reserved fish and shrimp to tomato mixture in cooker. Cover and cook for 15 minutes or until shrimp turn opaque. Stir in clams. Garnish each serving with lemon wedges and basil.