Lightly coat a large skillet with cooking spray. Place over medium-high heat. Sprinkle the trout with the salt, and season with pepper; gently place 2 fillets in skillet, skin sides up. Reduce heat to medium, and cook until undersides are golden brown, 4 to 5 minutes. Carefully flip fish, using two spatulas if necessary. Cook until fish is slightly flaky in center when poked with a fork, about 2 minutes more. Transfer fish to a platter; keep warm. Wipe out skillet, and repeat with remaining 2 fillets.
Wipe out skillet; add oil and almonds. Cook over medium heat, stirring, until almonds start to turn golden, about 1 minute. Remove from heat, and immediately add parsley and lemon zest; stir to combine. Stir in lemon juice; as soon as it starts to bubble, pour sauce over fish.