Strong, oily fish like salmon go well with acidic juices/sauces - lemon, red wine, vinegar, tomato. Hollandaise sauce is a traditional lemon one (although too much butter for a bodybuilder), red wine reduction (again with butter, but you can be sparing). Salmon Putanesca (so named because it was traditionally served by prostitutes to their clients) - with olives, capers, and pasta, in a tomato sauce is good and easy if you just buy some Paul Newman's.
White fish will benefit from asian marinades. I don't really eat much white fish tho, it's kind of dull. Swordfish marinated in teriyaki, soy, and fresh ginger is great.
For tuna, just open can, chew, chase with water.
Or mix it with cottage cheese - makes it easier to eat without the fat of mayonaise.
