I'm also thinking that my "does this make sense?" circuit wasn't active enough.

I had a feeling that herring were larger than sardines, but it got overridden by the authoritative-sounding claim that they were two names for the same fish. In fact, I've eaten both canned sardines and pickled herring,. It's obvious that the latter is slices of meat which are bigger than whole sardines-- and I completely forgot sensory experience in favor of the words.