1. Preheat oven to 450°.
2. Peel shrimp, reserving shells; set shrimp aside. Combine shrimp shells, chicken stock, 2/3 cup water, and saffron in a medium saucepan. Bring to a boil; reduce heat, and keep warm.
3. Combine chopped tomato, onion, 1/2 teaspoon salt, sugar, and garlic in a food processor; process until smooth.
4. Heat a large ovenproof skillet over medium-high heat. Add oil to pan; swirl to coat. Add tomato mixture to pan; cook 6 minutes or until liquid almost evaporates, stirring occasionally. Add uncooked rice to pan; cook 3 minutes, stirring frequently. Drain stock mixture over a bowl; discard solids. Add stock mixture to pan; bring to a boil. Cook over medium heat 12 minutes or until rice is tender and liquid is absorbed (do not stir). Top with reserved shrimp, tilapia, and peas. Sprinkle with remaining 5/8 teaspoon salt. Cover and bake at 450° for 15 minutes or until fish flakes easily when tested with a fork. Sprinkle with parsley; serve with lemon wedges.