I go to a fish store every weekend for the past month, I live in the area.
Reef Encounter - I was not impressed, very dark/small and dirty tanks. I saw a handful of dead fish in there....
Fishtown - Great for plants, and some "special" specimens and shrimp (I go to this place for shrimp)
and some place in Clifton on Rt 46
Scotch Plains area has a good one according to one of my mates.