In a small bowl, combine the soy sauce, oil, vinegar, garlic, ginger and pineapple juice.
Place the fish in a shallow baking dish and pour on the marinade. Cover and marinate in the refrigerator for 2 Hours, turning the fish once.
Remove the fish from the marinade, reserving the marinade. Grill the fish for about 5 minutes on each side, or broil it for a total of 10 minutes.
In a small pan, bring the marinade to a boil; reduce the heat and simmer for 5 minutes. Serve with the fish.