From everything I've read there's a lot of confusion about these guys. Most seem to think they're actually brackish rather then freshwater fish which causes confusion considering their common name. Scientific names unfortunately are equally as confusing as there seems to be several fish that are often referred to as the freshwater lionfish/toadfish. I've seen people identify the freshwater lionfish/toadfish as Batrachus trispinosus, Alenbatrachus grunniens and even Notesthes robusta. Notesthes I believe being the least likely depending on your location and living in NY I'm guessing it's not a Notesthes you've obtained.
I believe the most often freshwater lionfish/toadfish offered for sale is probably Batrachus trispinosus or Alenbatrachus grunniens and even that can in error on my part as there's so much confusion that people accidentally use them as junior synonyms for each other even though as far as I know they aren't true junior synonyms. Never mind the fact that it may be another fish that hasn't been often associated with common name freshwater lionfish/toadfish. That being said looking up either of my suggestions will lead you to similar results in care and often people's lack of success in keeping them long term. It's probably because of the misunderstanding of water requirements for them due to the often inability to accurately identify the fish obtained and the poor and inaccurate info. that's available online.
The only bit of info. that's probably accurate is that they're highly predatory, only taking live and perhaps frozen foods. As far as him not eating I'd check water parameters and would consider adding salt to the water since if he is a brackish fish he maybe already reaching his tolerance for being kept in fresh. Another thing you can try is feeding after light out as it's also been sugested that these guys maybe naturally nocturnal hunters.
Here's some reading readily available on google that I hope maybe helpful. It however shows the confusion I was talking about.
http://www.monsterfishkeepers.com/forums/showthread.php?154653-FRESHWATER-STONE-FISH!
http://www.seriouslyfish.com/species/allenbatrachus-grunniens/
http://aqualandpetsplus.com/Oddball, Stonefish.htm
My apologies for not being more helpful as my experience with these guys is limited to keeping one for a couple of months before he perished and it was when I was a less responsible fishkeeper. I never tried keeping one again and as such my knowledge about them is extremely basic at best and should be taken with a grain of salt.