Hope I get to you in time. The blocks long line for carryout makes it easy to know the Packing House has a great fish fry. It is right across the street from the airport.
Serb Hall, on 60th and Oklahoma, is a nice standard kind of fish fry.
I like going to Benno's on Greenfield Ave. in Greenfield. Not a huge or popular place but they have several different types of fish and preparation, not just stuck with beer battered cod, and they serve potato pancakes with applesauce.
Don't forget about Mader's or Usinger's for a true German-Milwaukee flair.