What size tank do you have your fry in and how many do you have? What type of filtration are you using and how often and what amount of water changes do you do? Also what temp do you have the tank set at? How often are you feeding per day? Do you notice the bellies of the fry becoming orange after feeding? You are bond to loose a few here and there, the weeker one's tend to not make it, too much competion for food. I can honesitly say that the angel fry that I raise I have never noticed any fry not wanting to eat the live brine, it is usually when you try to ween them from the brine to flake that they spit it back out.