Most of the fishing in NW PA is put/take fishing for stocked rainbows, browns, and brooks. The Allgheny National Forest in particular has significant plantings of fish which are advertised on the PA Fish & Game website. There you will find stocking lists and latitude and longitude of the streams listed.
Pennsylvania Fish and Boat Commission Home Page
There is ample camping in the ANF with campgrounds as well as rustic camping.
If you desire to hunt for wild fish, there are options for chasing wild brookies in the mountain streams. Expect steep hikes up small mountain streams for small but beautiful brookies. A 6 incher is a trophy in these waters and the scenery can be spectacular.
Look at Forest County, Warren County and to a lesser degree Crawford County. If you push to McKean and Potter you will get into more water that has wild fish options.