I would recommend any white fish for frying. My fish of choice would be true cod or, if you are very lucky to have it, halibut. If you can get it, wahoo fries up wonderfully. Haddock works. Of fresh water fish, walleye is an excellent choice. But you could do this with catfish and get great results. Dust the filets with flour, coat with egg, dredge in Italian bread crumbs (season them to taste). Pan fry the filets in about a half inch of very hot peanut or grape seed oil (both have hight smoke points, which make them very good for frying). Remove when golden and then drain on a paper towel. Serve hot, with lemon, salt, and garnish.