Sprinkle fillets evenly with 1/4 teaspoon salt and 1/8 teaspoon black pepper. Place fillets on grill rack coated with cooking spray; grill 6 to 7 minutes on each side or until fish flakes easily when tested with a fork. Remove fish from grill, and flake fish into bite-sized pieces.
Combine fish and remaining ingredients in a medium bowl; toss gently. Cover and chill at least 2 hours.