Feeding New CPDs…please help!

I got 7 healthy CPDs online four days ago for my 10 gallon tank. They obviously hide when I make sudden movements, but then they come out to play in the front if I sit quietly. They are very active. The problem is that they hide when I try to feed them. I tried waiting for them to come back out before I drop the food in the water, but that didn’t work. They saw my arm and decided that was a threat. I’ve been feeding them .5 small pellets from New Life Spectrum. A few brave ones catch a pellet as it’s falling. More often, though, the pellets fall to the gravel. The gravel is black, so they can see the pellets, but I’ve noticed that they just pick at them and spit them out. When they catch them as they are falling, they don’t spit them out. How do I successfully feed these guys? I don’t want to try live food because I’m afraid of parasites. I tried freeze-dried bloodworms, but those float no matter what I do to make them sink. I’m so worried about them! How will I know when CPDs are too skinny? I’ve never seen one. Please help!