Flashing off of rocks and decorations usually mean gill flukes or an irritant in the water. They seem to small to be flashing off of things due to flukes. Maybe they're actually trying to graze off of stuff in the tank?
I would recommend hatching BBS for them, too, or maybe trying some decapsulated brine. Fry that small really need something tiny to eat, and the live BBS will usually stimulate the fry to go after it. I've found that not all of my small fry will take non-live foods. I raised one spawn of severums on live BBS and they all ate, but then I tried another spawn on decaps and only about 50% of them ate it. The rest wasted away and died.