When my son was playing volleyball in Sweden, he said they ate all sorts of fish .. for breakfast! He was never a picky eater, and he caught on fast. Some of that fish that I read about sounded plain stinky!
I've eaten fish for breakfast my whole life but I am Swedish-American. There are some fish preparations eaten in Scandinavia that are a bit exotic because they are partially.....well....rotted but the end result is a lot more like cheese than zombie fish. It's perfectly safe although it may explain some of the day-drinking that goes on over there. :D