Food for thought (oh, that's punny!)...
Way back in the day (likes 60's/70's), commercial fish foods were typically of a lower quality so a combination of many live foods were a better way to provide fish with the best nutrition. Still today there are many commercial fish foods that use lower quality fish-meal with copious amounts of starch from grains as filler/binder. Often some grain (wheat, oat, rice or gluten) will be listed as the 1st or 2nd (primary) ingredient in the ingredient list.
The trouble is the poor quality of some fish-meals and unlike fresh fish and plant matter, fish can't really digest grains so it just passes through as excess waste.
However, nowadays there are several high quality commercial fish foods to give our fish a balanced diet. (I remember way back when I switched to higher quality foods, my fish suddenly produced much less waste! ... and less waste means a cleaner tank with lower nitrates)
Daphnia is not a very nutritious food source so use as a treat or be sure to also feed many other live or frozen foods and/or a high quality commercial food.
I have never setup a daphnia tank, but understand they feed mostly on algae, so you'd typically setup a tank in the sun before adding the daphnia culture and/or you might grow algae in a jar(s) to feed. I'd also think feeding spirulina powder might be better than yeast.
