Cook quinoa per package directions.
Season fish with ½ teaspoon salt and ¼ teaspoon pepper, then brush 1 tablespoon nonfat Greek yogurt on each.
Mix whole-wheat panko and chopped pistachios with 1 tablespoon olive oil; sprinkle over fish, pressing gently to adhere.
Bake on a nonstick foil-lined rimmed baking sheet at 375°F until opaque throughout, 12 to 15 minutes.
Fluff quinoa, then add baby spinach, lemon juice, 1 tablespoon oil, and ¼ teaspoon each salt and pepper; toss to combine and serve with fish.
