How to Raise Daphnia and Moinas

How to culture Daphnia and Miona successfully 

In this video, I will explain to you how to successfully culture Daphnia and Moinas using green water and spirulina powder.  I will go over techniques use for the culture, including culturing green water as well as common mistakes on why Daphnia/Monias culture crash.

Key takeaway

• The best food source for Daphnia and Moinas is greenwater from the genus Cholera.
• Spirulina is probably the best source of powder food if you are not willing to culture green water.
• Airline tubing are your friend, water circulation helps with keeping the water well oxygenated.  
• Daphnia/Moina culture crashing happens fast and it is cause by the build up of waste, particularly Phosphate in the water.
• House them in a large tank, the bigger the better.

Culturing green water

Culturing greenwater is a lot simpler than what most people think.  There are certain things that need to happen for green water to occur and that is.

• Nutrients, particularly Ammonia and Nitrates
• High light intensity and or photoperiod
• High PH and high calcium and magnesium content

The Greenwater algae that we commonly culture on purpose or often by accident is Cholera sp. (various species exist).  Both plants and Cholera uses photosynthesis to reproduce and grow but they have different limitation.  Plants need a rest period for them to convert the sugar in their cells to starch.  Cholera sp is a much simpler group of organisms that do not require a rest period to continuously reproduce.  So in a situation where light is very intense and there is a prolonged photoperiod, Cholera will proliferate.  Likewise, if the photoperiod is too short (less than 8 hours) Cholera will struggle to proliferate.  Because of this, I advise people to leave the culture of Greenwater outdoors or extend the photoperiod indoors by leaving lights on over the water for more than 12 hours.

To start my culture I simply save the waste water when I vacuumed my tanks.  Fish waste is a great source of nutrients for the Cholera sp. because it is high in ammonia and nitrates.  If you don't have a chance to do this, you can also add in most types of plant fertilizer, in fact with the addition of my wastewater I also always add this in.

One important thing to note about Cholera sp. is that they like to have hard alkaline water.  Because of this, I always add in tap water.  I live in southern California so the tap water here is always hard.  Alkaline hard high mineral content water will always produce a much greener thicker culture of Cholera sp.  Besides, Daphnia needs to have highly alkaline hard water to survive, Moinas can tolerate softer water but they still proliferate much better in harder alkaline water (high PH and GH).

Keeping Daphnia and Moina alive.

One of the biggest mistakes many people do when they culture Daphnia and Moinas is they do not do enough water changes.  Daphnia and Moinas produce waste, particularly phosphates.  When the phosphate level of the water goes too high, daphnia and moinas will die extremely fast.  When your culture start to crash it will happen within a day or two.  Because of this, I always recommend everyone to do partial water changes when there's an indication that the water is going bad.  One of that indication is when the water turns brown and the green water is starting to fade out.  When this happen you need to change water on a daily basis with fresh green water or tap water(dechlorinate) and start using your daphnia.

Another thing you should do is run an airline in your culture tank, water circulation is always a good thing, and having well-oxygenated water keeps the population density high.

Raising Daphnia and Moinas indoor using spirulina

For those of you who are for whatever reason unable to culture green water, you can successfully culture them indoor.  The first thing you need to think about is the food source.  There are many different type of food source you can use for indoor culture, these includes Yeast, flour or even protein powder.  however, the best food source is in my opinion Spirulina powder.  Spirulina powder is a Cyanobacteria that is a blue-green in color, think of it as free-floating blue-green algae.  Spirulina powder are also highly nutritious, they are very similar in nutritional content as green water and are high in vitamins, particularly vitamin B12.  Vitamin B12 is one of the most vital vitamins for many organism and fish are no exception.  What you feed to your daphnia and moinas will eventually transfer to your fish.

To set up a culture tank, use at least a 5 gal tank (10 gals prefer) and fill it up with tap water.  I use tap water because it is naturally alkaline and hard where I live, if your water is naturally soft, you need to increase the hardness or alkalinity with KH and GH booster.  Make sure you dechlorinate your water before using or else the Daphnia or Moinas will die.  Once you have done that you should run an airline through it to circulate the water before putting your daphnia.

When feeding your Daphnia, make sure you do not use too much spirulina powder.  For every 5 gal I have, I use about 100mg (milligrams not grams!) or a pinch of spirulina.  I mix the spirulina in a separate cup of water before pouring it into the culture.  The airline tubing keeps the water circulated enough that the spirulina powder does not settle, this is what you want because if the powder is settled the daphnia has a hard time reaching its food.  Most people make the mistake of using way too much spirulina powder, you have to remember that the spirulina you buy online is dead they will rot in the water and kill the daphnia.

Just like with the Greenwater method, you want to change out the water every few days.  For a very dense culture, you might have to change it out every day.  I use a brine shrimp net where I pour out the water so that I do not lose any daphnia/moinas when doing water changes.