Yes many species of fry eat the stuff. Many species in all eat it, including daphnia. Yes, it can be an important base link in the food chain. That is why blooms of plankton are so vital for a pond. Either plant and or animal. Bear in mind fry just do not have a lot of food choices. There is not very much that will even fit into thier mouths, and that yolk sac is gone real quick. And in turn, they get eaten by bigger species. I think if your desire is a sustained close to balanced pond and food chain, you need both blooms.
