The daphnia culture doesn't need much oxygen to thrive. Containers kept outside with a large surface area don't need any aeration at all. Containers kept inside should have very light aeration(just enough to break the water surface). Too much aeration(bubbles) can kill off your culture.

Do daphnia need air pump?

The container must be well aerated; this is commonly accomplished with the use of an airstone powered by an air pump. Make sure that the container is aerated for at least 48 hours before introducing the Daphnia. ... Spring or bottled water can also be used for the Daphnia. Be sure to provide light for the Daphnia cultures.

Do daphnia need oxygen?

Because Daphnia do not have a complex respiratory system, they generally obtain oxygen for respiration through diffusion. Oxygen molecules along with water are carried in and out through the outer carapace of the Daphnia. ... This allows the Daphnia to survive in hypoxic (low oxygen) water conditions.