there was a nice lfs out in aston, near the pa/de border, called aquarium world. i went there a few months back. guy was helpful, had some nice stock and driftwood.
also was a place near wilmington called greenbanks aquatics. had some nice larger cichlids, synos, other good stuff.
There is Fish Factory which is practically down the road from Hidden Reef.Those two shops are not inside of Philly's boundaries and there really is nothing worth wasting your time for inside the city anymore.
If you are willing to get over the bridge to the Jersey side, there is Aquarium Center in Blackwood 15 min from the Walt Whitman Bridge. Aquarium Center is the finest LFS in South Jersey/Philly region that offers great choices at good price.
If you are looking for Asian fish similar to the former Giant Aquarium,there is a new Asian store in Baltimore, Lucky Aquairum, that is worth the drive. On the same trip, you can visit another great LFS, House of Tropical, near Baltimore airport.