Fish Tacos? Aurora/Naperville
Thanks for the mention Mugs. Fish tacos are not something very common in the area. You could try El Tesoro in West Chicago on Roosevelt, they specialize in Mariscos, but I don't remember fish tacos on the menu.
The best fish tacos I've found in the area are at Chick's n Salsa near the intersection of Roosevelt and Rt 53 in Glen Ellyn. Although it isn't a quick drive from Rt 59 and I-88 I find that their chicken and fish tacos make the trip worth it.