For sale here is a vial of 100+ daphnia eggs.
Culturing instructions: Add the eggs to a jar of green water and gently stir. Keep the jar in a well lit area and provide gentle aeration. Some of the eggs will hatch within a few days. It is normal for only a small percentage of the eggs to hatch. The unhatched eggs can be collected and stored in the fridge for a couple of weeks. Subsequent attempts to hatch the remaining will produce additional baby daphnia. This is a survival strategy that allows the daphnia to survive in small ponds/puddles that may dry up between rain storms. The best food for culturing daphnia is green water or algae paste. In a pinch small amounts of yeast or very fine spirulina powder can be used.