I think the worst thing I ever tried to eat was a raw shrimp (I was in Japan then). An associate at the time said he swallowed one and his stomach rejected it instantly.
I like Swedish-style pickled herring, though. My mom used to make it with fresh fish, and it was great. The store-bought stuff isn’t as good.
That’s it for raw seafood.
I was sick for 3 days from some fried clams. Haven’t touched them since.