Could it be maltaise, mousseline, bearnaise or moutarde

I would tend to go with the mousseline with cooked shell fish, could also be used with salmon wellington, or over grilled salmon; or for that matter any firm fish such as halibut.

The sauce I tend to use quite often for just about anything, is basic white sauce made with melted butter, flour blended in to make a roux and milk in moderation while it is thickening, or depending upon how thick or thin you want it to be. This basic white sauce would be served with lots of fresh ground pepper added, very little salt, because you would be depending on the salt in the butter. Can also be used for steam puddings, only add a small amount of sugar.

Tick

It depends on the fish used in the dish. The sweetness of the whipped cream, the zest of the citrus, or the sharpness of the mustard would flavor the sauces differently.

emulsion = the stable distribution of microscopic droplets of one liquid in another liquid with which it normally doesn't mix

hollandaise = egg yolks, clarified butter, lemon juice, salt, cayenne pepper

maltaise = hollandaise, orange juice, blanched mandarin orange zest

mousseline = 3/4 hollandaise sauce and 1/4 whipped cream

bearnaise = egg yolks, clarified butter, lemon juice, salt, tarragon, chervil, a reduction of white wine vinegar, shallots, peppercorns and tarragon

moutarde = hollandaise and mustard

I have only tried the hollandaise and Bearnaise with veggies and beef.
I bet the other two are scrumptious:)

It depends on the fish used in the dish. The sweetness of the whipped cream, the zest of the citrus, or the sharpness of the mustard would flavor the sauces differently.

emulsion = the stable distribution of microscopic droplets of one liquid in another liquid with which it normally doesn't mix

hollandaise = egg yolks, clarified butter, lemon juice, salt, cayenne pepper

maltaise = hollandaise, orange juice, blanched mandarin orange zest

mousseline = 3/4 hollandaise sauce and 1/4 whipped cream

bearnaise = egg yolks, clarified butter, lemon juice, salt, tarragon, chervil, a reduction of white wine vinegar, shallots, peppercorns and tarragon

moutarde = hollandaise and mustard

About what proportions for the maltaise? And the moutarde please?

I swear by epicurious recipes --

This will work for broccoli too.
Maltaise Sauce for Asparagus Recipe at Epicurious.com (http://www.epicurious.com/recipes/food/views/Maltaise-Sauce-for-Asparagus-10376)

For salmon --
Salmon a La Moutarde Recipe at Epicurious.com (http://www.epicurious.com/recipes/member/views/SALMON-A-LA-MOUTARDE-1200923)