Daphnia - Can you avoid the crash?

kribensis12

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Hello friends.

I am anticipating setting up a 10g to raise Daphnia in - I intend to use them as live food for all of my fish but especially fry.

I have reason some very interesting articles (scientific and not) on what to feed, how often, environment etc....

With that being said, every person that I know who has cultured Daphnia has referred to the population crashing and they have to start completely over.

SO my question is: Can you avoid the crash?

Thoughts, tips, links etc. are appreciated! I expect @AbbeysDad will have a lot to say on this topic!
 

itiwhetu

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Simply No. Have multiple containers the more the better and split your population over them. I used to work on around twenty containers, and I still had to collect from the wild from time to time.
 
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kribensis12

kribensis12

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Simply No. Have multiple containers the more the better and split your population over them. I used to work on around twenty containers, and I still had to collect from the wild from time to time.

Do you happen to know what causes the crash?

I've heard of aquarists going several months and then one day - boom. Crashed.
 

itiwhetu

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@Colin_T will be able to help you he has always managed to produce consistent green water, which is something I have never achieved. It will be interesting to find out how he does that.
 
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kribensis12

kribensis12

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I believe lack of food, they starve themselves to death. They have very particular food requirements which I don't fully understand.
I have heard very different things from different sources which is why I am asking. I wonder if someone has experience in a culture that didn't crash or at least not for a very long time.
 

Colin_T

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There are several reasons Daphnia cultures crash.
1) poor water quality.
2) temperature.

1) Poor water quality.
Most people set up a Daphnia culture and let it run. They don't do water changes, they just feed it and leave it. Eventually the water quality goes bad and the culture crashes. You can reduce or prevent this from happening by doing regular water changes and having an air operated sponge filter in the container. Having some shell or beach sand on the bottom of the culture can help to stop the pH dropping suddenly too. If you keep the water quality good and don't let the pH fluctuate, the culture will last longer.

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2) Temperature
Daphnia normally occur in winter or spring (depending on country). They appear after the ice freezes in really cold climates, or in winter in hotter climates.
Their natural life cycle goes:
  • Dormant eggs hatch when it rains and the pond fills up, or when ice melts.
  • Daphnia grow and become sexually mature within a few weeks.
  • Female Daphnia produce clones of themselves, which are born regularly.
  • As the water warms up and starts to evaporate, the Daphnia produce dormant eggs that are released and sink to the bottom. The dormant eggs can survive drying out and will hatch when it rains the next time.
If you keep the water temperature at a stable level (not too hot, not too cold), the culture will continue to reproduce with clones.

If the water temperature gets too warm, the females produce dormant eggs and the culture crashes.

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As mentioned by @itiwhetu, having a number of cultures going at the same time is the safest method because you can fall back onto the newer cultures if/ when the older cultures crash.

If you start a new culture every 2-4 weeks, you should have a steady supply of Daphnia.

If a Daphnia culture does crash, let it dry out and then put a cover on the culture. Leave it for 3-6 months and then fill it back up with dechlorinated water. The dormant eggs should hatch and you can start another culture.

You can also scrape the algae, eggs, dead daphnia and other gunk off the bottom of the culture container when it's dry, and put it in a plastic bag and save it for later on. Then add the contents to a container of green water to start a new culture.

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The following link has information on culturing live food for baby fish and includes green water, infusoria, Daphnia, Rotifers and a few other things. Daphnia and freshwater rotifers can be cultured in the same way, either in green water or infusoria cultures. Green water is the better one to use.

NB, green water cultures should be started regularly and fertilised with a liquid aquarium plant fertiliser regularly to keep them going.
 
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kribensis12

kribensis12

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That’s good insight @Colin_T — I have heard the argument that it crashes due to water quality. I hope to maintain a consistent yet safe temperature (~70 degrees) so that they clone but don’t make dormant eggs by default. Also I intend to do weekly WC like the rest of my tanks.

Thanks for your input!

Anyone else?
 
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AbbeysDad

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I have several articles on my first hand experience culturing daphnia...

Culturing Daphnia
The Outdoor Daphnia Bins
Daphnia Take 2
And here is an article on Daphnia by Greg Sage of Select Aquatics of Erie Co.

The answer to the crash question is YES, it can be avoided - I very rarely ever have a culture crash.

> Overfeeding and/or poor water quality is probably the number one reason for crashes. Daphnia are very sensitive to water quality. As a matter of fact, daphnia are sometimes used to test water for quality (...'believe it or not').
In my indoor cultures I do 50% water changes once, sometimes twice per week.

> Temperature is another issue. I have had outdoor cultures crash in summer during a heat wave. And of course in the fall here in the northeast US, as the temperatures fall, daphnia produce eggs for the next generation in the spring and the adults perish. They do well, although not over producing, in my unheated basement.

> I never use a sponge filter as it would remove the food before the daphnia can consume it. I merely use an air line with large bubbles as small bubbles must be avoided. In my outdoor bins bins I don't use aeration, but I do lift and pour deli cups of water following daily harvesting.

> I never could produce enough green water to keep daphnia cultures thriving, so I don't bother. I've also had poor results with yeast. I mix spirulina powder and pea powder in a reclaimed salad dressing bottle with water. I feed sparing daily, sometimes twice a day. In larger outdoor bins I'll have some fall leaves and toss in chunks of watermelon rind or zucchini as daphnia will also feats on bacteria. I tend not to do this in the smaller indoor bins as if/when the water becomes cloudy with a bacteria bloom, the daphnia may suffer and crash.

I have to say that my outdoor bins in season, especially the 5' kiddie pool produce large amounts of daphnia with mosquito larvae as a bonus!

For even more information, take a deep dive into Live Food Cultures.

I guess the above validates the OP's prediction about my having a lot to say about culturing Daphnia! :)
 

StevenF

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Have srimp and i found they would never reproduce. And eventuallyI would've online left and would have to get more. I eventually came to the conclusion my RO water was to blame. RO water has no minerals. Natural water has many things in it. So I did some research and found that lithium (Li), ,sodium (Na), selenium (Se) ,iodine (I), bromine (Br), and cobalt (Co) are nutrients that animals need in addition to the nutrients plants need. Since plants don't have those nutrents that means the water is the primary source. SoI tried putting very small amount of these in the water. My shrimp then started reproducing. I have managed to avoid population crashes. since.

Tap water typically has Li, Na, Se, I, Br, and Co. So water changes would probably help if you can find a way to keep them out of the discarded water.
 
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kribensis12

kribensis12

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I have several articles on my first hand experience culturing daphnia...

Culturing Daphnia
The Outdoor Daphnia Bins
Daphnia Take 2
And here is an article on Daphnia by Greg Sage of Select Aquatics of Erie Co.

The answer to the crash question is YES, it can be avoided - I very rarely ever have a culture crash.

> Overfeeding and/or poor water quality is probably the number one reason for crashes. Daphnia are very sensitive to water quality. As a matter of fact, daphnia are sometimes used to test water for quality (...'believe it or not').
In my indoor cultures I do 50% water changes once, sometimes twice per week.

> Temperature is another issue. I have had outdoor cultures crash in summer during a heat wave. And of course in the fall here in the northeast US, as the temperatures fall, daphnia produce eggs for the next generation in the spring and the adults perish. They do well, although not over producing, in my unheated basement.

> I never use a sponge filter as it would remove the food before the daphnia can consume it. I merely use an air line with large bubbles as small bubbles must be avoided. In my outdoor bins bins I don't use aeration, but I do lift and pour deli cups of water following daily harvesting.

> I never could produce enough green water to keep daphnia cultures thriving, so I don't bother. I've also had poor results with yeast. I mix spirulina powder and pea powder in a reclaimed salad dressing bottle with water. I feed sparing daily, sometimes twice a day. In larger outdoor bins I'll have some fall leaves and toss in chunks of watermelon rind or zucchini as daphnia will also feats on bacteria. I tend not to do this in the smaller indoor bins as if/when the water becomes cloudy with a bacteria bloom, the daphnia may suffer and crash.

I have to say that my outdoor bins in season, especially the 5' kiddie pool produce large amounts of daphnia with mosquito larvae as a bonus!

For even more information, take a deep dive into Live Food Cultures.

I guess the above validates the OP's prediction about my having a lot to say about culturing Daphnia! :)

Wow, thanks for that helpful information! I'm sending you a PM!
 

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