Actually, the only reports i've heard of needlenose breeding, have been in pure freshwater aquariums. Though, a slight change in salinity usually triggers them to court somewhat. In the pair I had, a slight water change with a low salinity would have them courting for the next few hours- but they never went through with it. [as a note, they're better of in freshwater than in brackish conditions]
My first attempt at fry was a little.. odd to say the least. I had almost no idea of how to go about it (i've never really heard of more than one person to actually raise them successfully) and it was sort of an experiment. They don't even eat for the first few days, and when they do, they usually won't even look at newborn brine shrimp. I had raised rotifers and copepods, including other random critters, which they seemed to eat for a while. Later going toward brine, and eventually a few ate eachother (the joys of carnivorous fish).
Bottom line, so I actually shut up, prepare to put a lot of work and effort into a small batch of fish, which you might get ONE to live a few weeks. If your willing to go for it, and have a breeding pair (which isn't so easy to find to begin with) then expect to have almost an endless opportunity to try n_n