I have never marinaded my fish. If fresh they are sweet allowing the flavor of the fish shine enhanced by theI marinade just before cooking.
One of our favorite is steaming a fish whole ( Yes whole for presentation . I do have a huge round double decker aluminum steamer for crabs, steaming siopao or chinese sticky rice and for fish if I do not mind cutting a big fish into 2 pieces and reassemble the fish after it is cooked for my family but I also have a rectangular steamer for a whole large fish , the kind they use in buffet which I prefer to use for presentation when I have guest. My 40 year old 62" vulcan range was custom made for me so that there is a 24" flat plancha like compartment for steaming or poaching fish so that I do not have to straddle on 2 of the cast iron plate which means no electric element between the plates as this plancha has electric element thruout. So, mainly, scatter smashed ginger, scallions , garlic black beans all over including the cavity and inside the head, soy sauce, cider vinegar, shaoxng wine, mirin , sesame oil all over and steam until the fish lose its translucency Usually 14 minutes after the water start boiling. The timing depends on the thickness of the fish. Our favorite is fluke( summer flounder ) or red snapper. I usually ask the fish monger to clean it , slash a pocket cavity for spices. I would score the fish a few times so that the marinade gets inside the fish.