My mother uses Helmrich's Seafood in Williamsport. She usually gets shrimp and haddock, which are fresh and wonderful. She said there are many items on the board, some she even called "strange".
The market is located just off of Little League Boulevard in Williamsport, west of Market Street in the area of the Pine Street United Methodist Church. She said you turn south on Pine Street off of Little League Boulevard, then make a quick right into a block that is mostly the seafood market and their parking lot. There's also a large bell tower that belongs to the church. If you pass the church on Pine Street, you went too far.
Hope that helps!