I'm in the Hamlet of Wallkill over by New Paltz. I have a 220 Reef in my basement, and a 100 Gallon Frag system chock full of stuff for sale and trade.
The stores are all over the river in Poughkeepsie.
Hudson Valley Fish N Reef is on Route 9. They are having a BBQ at the store august 27th from 12pm-5PM. That is where I get a lot of my stuff from coral wise. I will be there for the bbq, hit me up if you want to trade or buy some frags.
Aquarium Solutions 101 is in Wappingers Falls. They are on the expensive end, especially coral wise. Last time I was there the prices were higher than shops in Manhattan and Connecticut for coral. Fish pricing was ok.
Petco in Fishkill is good with fish. They have a young kid Mathias running the salt water section and he does a real good job with it. As with all Petco's, that's obviously subject to change at the drop of a hat lol.