I agree, and when I portion out things to freeze, portions of beef or pork are ~10-12 oz, but fish is almost always a pound. (I eat one large meal and one small snack a day.)
Aside from cream sauces, you might want to saute fish in good oils. Salmon is a bit more filling (to me anyway) than most other kinds of fish - probably from the fat content. Not sure of your position on potatoes and/or white rice, but either makes a pretty good side dish to fish, and topped with butter is pretty filling.
If you use primally approved flours, squid dredged in tapioca flour and fried in a good oil is pretty terrific. (Cut it into rings first.) I think shrimp might work that way too, though I usually eat head-on shrimp just boiled with spices.
And as always, watch for sales and be open minded. If I'm trying something new, I'll ask the fish monger by cluing her/him into what I like/dislike (eg. I really don't like Snapper). A good fishmonger should be able to point you in the direction of a new and maybe less expensive fish. Catfish cheeks are usually inexpensive and can be prepared like any white fish.
A lot of people here like sardines in cans. Good for you. Portable. A little expensive if you prorate the cost of a can over a pound, but for some reason canned fish is really filling, even when packed in water.
Hope some of those are helpful.