Prepare Pineapple-Cucumber Salsa; cover and refrigerate, if desired, until ready to serve.
Place fish in a large heavy-duty, zip-top plastic bag. Combine soy sauce and next 4 ingredients; pour over fish. Seal bag; turn to coat fish. Marinate in refrigerator 30 minutes.
Coat grill rack with cooking spray; place on grill over medium-hot coals (350° to 400°). Remove fish from marinade, discarding marinade. Place fish on rack; grill, covered, 4 minutes on each side or until fish flakes easily when tested with a fork. Place fish on 4 individual serving plates; top each serving with 1/2 cup Pineapple-Cucumber Salsa. Garnish with cucumber slices, if desired.