no, I just add a pad of butter, and smear some pesto. Add more pesto when it come out of the grill. Difficult to find halibut here in the County but it is a favorite dish.
I also love chilean seabass which is a favorite. I love it seared with just a little peanut oil till it is blackened and crusty, take the fish out, add ginger, garlic and spring onions ( sometimes I add those towards the end of searing as the seabass is a very oily fish and the oil that comes out is full of omega. ) , then add miso, a splash of white wine if available or if not, shaoxing wine, a splash of mirin , which counteracts the saltiness of the miso, a small amount of broth ( I have the habit of using vegetables when they are peeled plus asparagus ends and roasted shrimp shells to make broth ) Leave that on the stove for just a minute or two, and as it is thickening, place the fish back on to the frying pan, serve immediately right from the frying pan to be served with kokuho red rice. That is a favorite dish here in my home.