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Culturing
The most critical environmental factor when culturing Daphnia is temperature, which should
remain as close to 20°C (68°F) as possible. Higher temperatures could prove fatal to the organisms,
while lower temperatures slow reproduction rates.
Daphnia flourish best in a large container with a 10- to 100-gallon capacity, although containers
with a one-to five-gallon capacity will suffice if the population is monitored closely and subcultur-
ing is done frequently. Use pond or spring water; allow the water to sit undisturbed for several
days before adding the Daphnia to ensure that all air bubbles have escaped from the water. Any
air bubbles in the water may become trapped beneath the Daphnia's' carapaces, lifting the animals
to the surface, where they will die. If this happens, sometimes gently pushing the Daphnia back
below the surface will release any trapped air. You may also prepare a container for Daphnia by
covering the bottom with a thin layer of peat humus and filling the container with hot tap water.
Allow the water to sit undisturbed for 48 hours.
Introduce a relatively large "seed" culture to the water by immersing the jar, upright, in the water.
Empty the jar underwater to keep any air from entering the water. Then stir the surface of the
water to break up any film that forms; the film will block oxygen exchange between the water and
the air.
Care and Feeding
Daphnia feed on smaller protists. Add approximately five drops of a Daphnia growth medium
per gallon three times a week, or add Euglena to the culture twice a week. Keep feeding schedules
consistent. Avoid over-feeding, as extra food will foul the water.
Some populations prefer sunlight, providing the temperature of the water does not rise, while
others do just as well without sunlight. D. magna flourish in diffused or indirect light.
Perform a partial water change (about half the amount) once a month. Subculture at least every
two weeks to prevent overcrowding, production of males, and development of ephippial eggs.
Harvest populations regularly using a net with a mesh large enough to remove most of the adults,
yet leave behind the developing Daphnia.
© 2021 Ward' s Science. All rights reserved. Rev. 2021
