Fish happens to be be one of my favorite foods. I think I am in the minority in US. I also like beet soup (borscht), so hopefully I am getting my share of Fe as well.
A lot of people here love steaks, chicken, spaghetti, pizza, but fish or beets are secondary or fall in the "weird" foods category.
In general I think so many Americans have weight problems because the popular foods happen to be bad for them. An extreme example of this is the Native American food -- fry bread. They have been displaced from their lands, and US govt. is feeding them with lard and flour. No wonder diabetes rates are so high among that population segment.