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Moina Culture

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I started setting up my pair of moina cultures today.  My goal is to produce enough to feed my two small display tanks daily and to use them in place of BBS for the raising small numbers of fry.  Hopefully, the built-in spigots will make harvesting super easy.

I have a pair of 2.5Gal water dispensers and I've kicked things off with:

  1. Some gunk from an established aquarium's filter
  2. API quick start
  3. Boiled veggies and resulting water
  4. A handful of crushed coral
  5. A few snails
  6. An airline blowing coarse bubbles

After the water get's a little funky, I'll add the moina from some small cultures I've been running.

I have a variety of things in mind to try:

  1. Adding a small gravel filter
  2. co-culturing dero worms
  3. co-culturing black worms
  4. floating plants to keep nitrates down
  5. Adding emersed plants whose roots will soak up nitrates and provide more surface area (which is supposed to boost moina production)

Anything else I should think about trying?


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Three updates:  Bacteria blooming (and smelling), preparing food, and culture contaminants

Bacteria Bloom

After a few days, things got quite cloudy, which indicates a bacterial bloom, which is good news.

Unfortunately, I discovered a problem:  when I prepared the boiled veggies, I just grabbed whatever was in the fridge and going bad.  In my case, this includes some brussel sprouts.  So, no my office smells like mouldering cabbage...  oops.  Lesson learned, and I may have to start over.

Contaminated Cultures

I took a close look at my existing 1-quart moina cultures.  Both are contaminated with cyclops, so I'll start my new cultures with eggs from Greenwater Farm (available on amazon) and try to up my bio-security game.

Moina Food Prep

On another front, I've been experimenting with what to feed them.  I've been using the blend of spirulina powder with garbanzo, pea, and wheat flour suggested by Aquarimax Pets on YouTube.

I've tried preparing it in three ways to feed my small, established moina cultures

  1. Sprinkling the powder on the surface (cause I'm lazy)
  2. Stirring it into water and adding it drop by drop (which is what Aquarimax suggests)
  3. Using an electric whisk to mix it really aggressively.

With the first two I noticed lots of small-but-visible spirulina particles that sink quickly:


However, with the whisk, the water just looks green and stays in suspension better:





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I fished out the remains of the vegetables -- they had all been reduced to blobs of snot, but amazingly they didn't stink at all.

I put a few drops of the water under my USB microscope.  The pictures didn't come out, but there were tons of infusoria scooting around.  Once the moina hatch, there will be a great feast.


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  • 5 weeks later...

There's been quite a bit of progress (and some set backs) in my twin moina cultures.


Blooms and Flocs

Both containers accumulate lots of bacterial flocs and very thick biofilms.  I think these were trapping food particles so the moina couldn't get to them, leading to more spoilage.  It also make it very hard to see into the culture.  I also over-fed one culture, leading to an intense bacterial bloom (or maybe yeast -- I really want a microscope so I can tell the difference), which then led to a population crash.

Send in The Snails

The crash culture was having trouble recovering and the other had never really gotten off the ground, so I decide to shake this up by adding about 20 ramshorn snails to each culture (I got about 50 of them on ebay for $27).  What a difference!  In about a day, they converted all the bacterial flocks to snail poop, vastly improving visibility.

With a couple days one culture was teaming with moina and the other started a slow and steady climb in population.

Feeding the Snails

I was actually a bit worried by house quickly the snails cleaned up the bacteria, but then I remembered a picture I saw on eBay of a bunch of ramshorn snails eating a piece of watermelon rind.  We happened to having some for dinner, so I dropped a couple of pieces in.  Since then I've been feeding them melon rinds of various kinds, and they seem to be doing great.  I've noticed that if I feed the sweet parts (e.g., the red part of water melon), I get bacteria/yeast blooms, so I try to avoid that.

The snails seem happy: The walls are covered with egg masses.

I've also been feeding some of the pea protein/wheat flour/spirulina mixture, but I've stopped mixing it with water.  I just add a teaspoon every few days and let it disperse.  Seems to be working ok, and it's much easier.

Harvesting and Water Changes


My goal is sustainable harvest, and so far it's going ok.   Here's the daily routine:

  1. Drain 1 quart (about 10%) of the water from each culture through a brine shrimp net and feed to my 10 gallon.
  2. Top up with declor water.
  3. Dump the strained water in a 5 gallon "swamp bucket" with an air stone, a grow light, and a bunch of java moss.

Bonus Food Infusoria

One interesting side effect is that my 10 gallon tank (where I feed the moina) now has a very healthy population is infusoria.  At first I thought they were very fine air bubbles, but under magnification, they move on their own.  I assume the moina culture is full of them too and that is mostly what the moina eat.

I'm excited about this, since it means I have a ready source of micro food for fry.

If I can get black worms to grow in there, I could condition the parents and feed the fry all from the same cultures!


Edited by memorywrangler
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Disaster Strikes!  My Moina+Snail Symbiotic Culture Doesn't Like Leafy Greens!

After nearly a week of steady harvest (more than my fish could eat almost) and happy fish, we've had a serious population crash.

I'd been feeding the culture with watermelon to good effect, and I thought I'd mix it up and feed them some chard stems.  Bad choice, it seems.

The snails didn't like them, the stems turned mushy, and water turned very murky and yellow.  Yuck!  Then the moina population plummeted.



I did an 80% water change and it was so sad:  Usually drawing off a quart of water yields a feast's worth of moina, but 2 full gallons produced almost nothing.  🥲

Oh well, I'm sure they will recover.


Edited by memorywrangler
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