I think you’re thinking of Surströmming, which is Swedish and absolutely vile. (Properly prepared) Lutefisk is quite mild though definitely weird, even if you’re used to stuff like pickled herring. Ordinary pickled herring is fermented in brine (and own enzymes), intensity depends on age at the tail end of things you get fish sauce, Surströmming is fermented in lactic acid, Lutefisk is not fermented at all it’s stockfish (dried without salting) rehydrated in lye, then properly rinsed and cooked. It’s mostly the texture that’s weird.

If you find yourself in Scandinavia one thing to definitely try is elk salami.