Hello Inchworm,
I will be using the daphnia to feed my two angels. There are two live foods that I have found readily available at the lfs... bloodworms and fruit flies. They both work very well. I can also find brine shrimp but they're less convenient. My interest in the daphnia is to add a little variety to their diet. Also, I wonder if daphnia can survive in the tank... hiding among the plants and rocks... allowing for the inhabitants to forage for them throughout the day. I think the bloodworms can survive for a good while buried in the substrate, I have found them thriving weeks after a feeding. This works great for the loaches who dig in the gravel but the angels will have nothing to do with that.