Combine lemon juice, water, garlic, 1/4 teaspoon salt, and 1/4 teaspoon pepper in a small bowl; stir with a whisk. Gradually whisk in 1 tablespoon oil. Stir in parsley and oregano; set aside.
Sprinkle fillets with 1/4 teaspoon salt and 1/4 teaspoon pepper.
Heat 1 1/2 teaspoons oil in a large nonstick skillet coated with cooking spray over medium-high heat. Add fillets; cook 5 to 6 minutes on each side or until fish flakes easily when tested with a fork. Transfer fish to serving plates; drizzle with vinaigrette.