I just witnessed someone eating ketchup on his gefilte fish this shabbos! I told him he is nuts and he told me I am!! Can I get some backing please!!!
I've never done it, and my first reaction on reading that was "ugh, that's disgusting." But come to think of it, it's probably not bad at (assuming you like ketchup.) Personally I don't care all that much for ketchup but I don't see how it's worse than any of the other dips and spreads I would eat my gefilte fish with.