My grandmother used to make lutefisk, I think with lye. She was pathologically cheap, so she probably used whatever industrial-grade sodium hydroxide they stocked at the fishermens co-op for cleaning boat propellers.
i was in Oslo a few years ago around December and some of the restaurants had posted signs that they had lutefisk. The locals I was with told me not to eat it under any circumstances (unless I was interested in fish-flavored jello).
