Maybe lutefisk counts, but I don't think so. Fermentation has to be done correct, else it is dangerous. That's where the gross feeling stems from; it has/had a purpose.

Lutefisk isn't fermented, and has a mild smell and tastes of unseasoned boiled white fish with a slightly 'off' aftertaste. While most people don't particularly like it, it is hardly off putting unless you find boiled fish in general off putting.

If so, I wouldn’t say it’s an acquired taste. It’s a bit fishy but even as a child I liked it.

Quite possibly. It's not the same as various jarred herring in supermarkets (which is usually... okay.); my mother in law makes hers with oil, onions, cloves, and bay leaf and it's very much the same as what I had in Warsaw. There is another approach (which I haven't go the recipe for) that is sour and a little sweet and has sour cream and green onions (and sometimes raisins, in the northwest). Those are good and a little exciting because I have them less often, but I like the oil and onions and cloves kind better.

> If so, I wouldn’t say it’s an acquired taste. It’s a bit fishy but even as a child I liked it.

Yeah, I agree, which is why I'm a little amused at how much surprise and enjoyment "lubie śledzie" seems to prompt.