There is no problem with smaller fish.But it also depends on how big the tank is.The smallest tank I would suggest is a 20 gal for a breeding pair,with some plants and driftwood to give them a sense of territorial division.Besides,neons are way too fast for them.
WoW JDc, I was just going to ask that question about keeping rams with neons and pristellas in my 60 gallon tank. Currently i have 6 pristellas, 6 neon tetras, 2 albino corydoras, 1 butterfly pleco, and 10 ghost shrimp. How many pristellas do you have? I think that pirstella tetras are very beautiful for being tetras.