An aspect of fish marinades that is believed incorrectly is that juices remaining plus the marinade after cooking are to be relished. Generally this isn't the case. The juices tend to be cloudy and have a less than pleasant taste, even bitter. For this reason many good restaurants discard the juices immediately the fish is cooked and replace the marinade with some reserved and is still fresh. It's an excellent tip and easy to do. Just remember to make some excess marinade and hold it in reserve while the fish cooks.
 
If a fish is cooked wrapped in foil, then the easiest way to remove the juice, is to open one end of the foil and tilt the contents so that the juice drains out and is discarded. Then go ahead and open the whole packet and pour over some fresh marinade. The replacement marinade can be warmed so as not to drop the temperature of the fish.

Barbecue Fish Marinade (soy sauce, lime, vinegar, garlic, sesame)
Fine Fish Marinade (white wine, soy sauce, garlic, brown sugar, Tabasco)
Fish Marinade (lemon juice, scallions, coriander/cilantro, pepper, ginger, rice vinegar)
Ginger-Soy Fish Marinade (garlic, soy sauce, rice vinegar, ginger)
Japanese Fish Marinade (sesame oil, soy sauce, lime juice, mirin, garlic, ginger, chillie)
Sweet - Spicy Fish Marinade (honey, soy sauce, lemon juice, sesame oil, chillie, pepper)