Mine feed on exclusively daphnia and random mozzie larvae and bloodworms collected from my cultures. They have bred continuously for the last 3 months and I have a nice range of fish in the tank ranging from week old to 11 week old juveniles that are 3/4 grown and have already developed adult colouration. The live daphnia definitely do the trick!
I should mention that I don’t sort the daphnia in any way. I use a fine net and scoop a little or a lot (depending on status of culture) and give it a rinse under running tap water, then drop it into the tank. Galaxies go nuts and are in excellent condition.
Another way I recommend is to feed BBS with the Brine Shrimp Corrals. Sadly, my Celestial Pearls tank doesn’t allow me to remove the unit for cleaning, but if I could I would!