Thaw frozen fish.
Remove skin and cut into 4 portions.
Drain pineapple, reserving 16 cup syrup.
Combine reserved syrup with soy sauce, salt, and dash pepper.
Place fish in a single layer in shallow dish.
Pour syrup mixture over fish.
Let stand at room temperature about 30 minutes, turning once.
Remove fish from sauce; reserve sauce for basting fish during cooking.
Place fish on greased rack of broiler pan and broil 4 inches from heat till fish flakes easily when tested with a fork, about 10 minutes.
Brush occasionally with sauce.
During last few minutes of broiling, place pineapple slices on broiler pan.
Brush with pineapple sauce and heat through.
Sprinkle nuts atop fish and pineapple slices.