Moina macrocopa - the “Japanese” water flea


Phylum Arthropoda (arthropods )

Subphylum Crustacea (crustaceans)

Class Anostraca (gill-feeders)

Order Branchiopoda (leaf-footed crustaceans)

Suborder Cladocera (water fleas)

Family Daphniidae

Genus Moina

Species macrocopa


Moina macrocopa
Moina close-up

General cultivation conditions

Buckets with a capacity of 5 - 10 litres (max. 20 litres) are advantageous, glass containers are not so suitable.

2 - 3 buckets are strongly recommended for breeding - with different preparation times - as it often happens that a well running breeding simply collapses within 1 - 2 days.


Fluorescent lamp, daylight.

Do not place small containers in front of fully sunny windows, especially in summer, as otherwise the water will heat up too much. The light from nearby aquariums or indirect daylight is completely sufficient.


Moina sp. reproduce very well at approx. 25 °C. Less favourable are 15 - 18 °C (reduced reproduction) and temperatures above 30 °C (overturning of the water).


Yeast, food algae, Preis-Microplan, Artemia rearing food, nettle or filamentous algae powder.

Preferably dry or baker's yeast slurried in a small amount of water, which is added drop by drop to the breeding tank until a slight turbidity occurs; the turbidity should/must (in contrast to Daphnia sp.) still be visible after a day, i.e. the Moina must be constantly "standing" in the food.

Breeding is very productive, especially at higher temperatures and when feeding twice a day. For a good breeding yield it is necessary that the flea surplus is harvested daily or at least every 2 days. With a 5 litre bucket batch, this may be necessary after a few days, at the latest after a week.

Yeast slurries should be used within a few hours (preferably on the same day). If stored unrefrigerated, it will spoil within 1 - 3 days and if added to the water fleas, the entire culture will die within a few hours!

Do not close the slurry container tightly! Fermentation gases will form which can cause the container to burst.

Breeding description

The conditions for breeding the Japanese water flea Moina macrocopa are basically similar to those for Daphnia species.

For breeding Moina, 1 - 10 litre containers are already sufficient, whereby "bucket breeding" in particular is very productive. Larger containers harbour the risk of the water tipping over. However, it is not necessary or possible to add filter sludge or snails. Snails generally do not survive the permanent turbidity!


Breeding runs optimally when the fleas spend most of their time at the surface of the water and thus indicate an oxygen deficit. However, this oxygen deficiency is necessary for mass breeding of Moina.

Moina does not tolerate fresh water - every time water is added or a new batch is started, it must be fed immediately.

Due to the large amount of moulting residue, a new batch of stagnant tap or aquarium water is essential after 14 days, max. 2 months (depending on feeding intensity). In most cases, however, it is only advisable to re-suspend the water when it becomes cloudy, beer-brown in colour. It is not necessary to transfer old water, but it must be fed carefully to immediately create a cloudy environment for the Moina.

The new water will produce new fleas more quickly if the old wall covering of the bucket is not removed.