Mishna B'rura 173:4 and Aruch Hashulchan 173:2 say we don't need to wash our hands between eating fish and eating meat. Do any latter-day pos'kim argue with this? Does any group practice this halacha of washing?
I think that R. Ovadia Yossef says it's good to do Mayim Emtsaiyim even if some poskim say it's not necessary since we use spoon, knife...
You can see in Yalqut Yossef (Kitsur Shulhan Arouch) hilchot Seouda. (For the end of your question, I practice this halacha)