As noted in our profile of the Celestial Pearl Danio [click the shaded name to see it], foods must sink as the fish does not (normally) come to the surface to feed. Hakari make a micro pellet food that would be ideal (for the adults) as it floats for a bit but will easily slowly sink. This is the only pellet-type food i have found acceptable to all my fish; they seem to love it.
Fry often find microscopic food, especially in well-planted tanks that are not over-cleaned. The thick plants also provide good hiding spots for the fry until they are large enough to feel safe in venturing out. Once they do, in addition to the micro pellets, newly-hatched brine shrimp would work, and possibly frozen (or live) daphnia. There are also fry preparations and infusoria sold in fish stores.
Byron.