“kol echod keminhogo “. I am an ahskenazi so I have never followed this minhag- although I do not mix fish and meat (as per sakonoh). BTW- this is why one has whisky/brandy after the fish on Friday nights.
The one genuine news I learned is that (from besalel) the sefardim eat swordfish! Now ,how about sturgeon? Would love to eat caviar once in my life….