Cover 2 large baking sheets with nonstick foil and place in oven. Heat oven to 450 degrees F.
Carefully spread zucchini slices in a single layer on prepared baking sheets. Drizzle with 2 tablespoons lemon juice and sprinkle with 1 tablespoon of the parsley and 1/2 teaspoon of the oregano. Roast at 450 degrees F for 20 minutes or until tender, flipping slices halfway through.
Heat a large nonstick skillet over medium heat. Add onion, remaining 3 tablespoons parsley and remaining 1 teaspoon oregano to skillet and spritz with nonstick cooking spray. Cover and cook for 5 minutes or until softened. Uncover and add lemon zest and garlic to skillet; cook 1 minute.
Pour wine or water, vegetable broth and remaining lemon juice (about 2 tablespoons) into skillet. Bring to a simmer over medium heat. Add fish to skillet and cook, covered, for 5 to 8 minutes, until opaque, carefully flipping halfway through.
Remove fish from skillet and pour some of the poaching liquid over orzo (if using). Serve orzo with fish and zucchini.