In the thread about the
47th-a-Thon Rene G talks about the many fish places on the southwest side-- we visited one, Mariscos Luis, and were served shrimp soup to start (see picture in the thread) which seemed pretty good to me although I'm not going to claim it was outstanding or better than the next place in either direction.
Anyway, the point is, it seems likely that good stuff is in that area, but no one's explored it in depth to know which is better than what. You could be the first...
Mariscos Luis
4225 W 47th St
(773) 843-3448