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Easy Indoor Daphnia Culture

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Got into a debate over live foods, so I snapped some quick pictures of my setup and decided to make this post for people having trouble with raising daphnia indoors. Here are some simple steps to follow to be successful:

1. Pick the right daphnia strain for you. Fish size, feeding frequency, breeding container space, are all factors to consider when deciding which species to get. I would generally recommend daphnia monia or daphnia magna when starting off because they are both very hardy and monia can maintain the highest population density. Monia are also tolerant to very low oxygen and pollutants. If you are not going to feed your fish often, or if you don't have a lot of fish to feed, then daphnia is NOT for you.

Here is a pic of my outdoor Magna culture. Temperature is 41F right now. They do well even in the Texas summers.

2. The set-up: Ideally, you want at least 2 cultures going in case one crashes. I would recommend no less than 5 gallons per culture to keep it stable. What I use are cheap 5 gallon paint buckets from Wallie world. I toss a sponge filter (sponge filters are KEY because they keep the water pollutant free and act as a bacterial food source for daphnia) into both of them and hook up an air pump. I have a gang valve on the air pump and keep the flow at around 5-10 bps. Daphnia population density also increases with regular photo periods, so light is important. I got a cheap $7 lamp with a CFL I had laying around to serve as this source. Heaters are optional, but a consistent temperature will produce a consistently high yield (and allow microorganisms and algae to grow). Lastly, keep a palmful of crushed coral, crushed sea shells, or cuttlebone in each bucket to raise hardness and aid in daphnia molts.

3. The culture: I like starting daphnia on green water. Yes, this is a giant PITA for most people. But when you get a culture (generally 700 count) it is good to keep a stable food source that your daphnia can breed and grow out of for the first week. I like to start off with green water, then transition into prepared foods. A common mistake is to just dump the daphnia into the green water you made. Do NOT do this, as they will suffocate and die. Always make sure you dilute your green water as follows: 1 part green water: 7-10 parts distilled,RO,aged aquarium, or aged dechlorinated water. I would also toss in a couple snails (1 mystery per bucket, 3 ramshorns, or 1-2 nerites) to aid in cleaning up waste. Optionally, you can toss in some plants as well (I use pothos because it grows fast, sponges toxins, and is drama free).

4. The food: This is a really simple step that most people like to over complicate. If you followed the steps above and started off the daphnia with green water, all you need is spirulina and yeast to keep it going. I like using 1 part yeast:2 parts spirulina when feeding. I always activate the yeast spirulina mix before adding to the water. Refer to this link on how to activate yeast: When feeding, use a turkey baster and mix while dripping. Only feed until you can barely see the bottom of your container.

5. Water changes: Honestly, once a week water changes on two 5 gallon buckets is over-rated. I go once a month with remineralized RO water (aged aquarium water/aged dechlorinated tap water is fine too) and do a 50% water change. My daphnia always explode in population right after. A good rule of thumb is that if you see daphnia population decline for no reason, do a water change.

6. Profit: Once your culture is going, make sure to feed your fish often. Daphnia populations will crash if they overcrowd your container. If you have more than your fish can handle, either sell them, donate them, or dry/freeze them and save for later. I usually cull from alternate containers about 100-200 every day.

7. Vacation: If you are going on a week long vacation, do a hard cull of your daphnia, leaving under 100 in each bucket. If you are going on a vacation for a month, turn off the lights, stop feeding your culture, and expose them to temperatures in the high 30s (F). This will cause them to make diapause eggs which will float at the surface. You can collect and dry these eggs (they look like tiny pea pods). When you come back from your vacation, hydrate these eggs in a restarted culture and you will have daphnia again!

Some disclaimers i'd like to dispel:

1. Daphnia cultures do not "randomly crash." There is always a limiting factor that is inhibiting them to reproduce. Whether it is low GH, water quality, lack of food, or whether you accidentally dumped 2 gallons of chlorinated water in your container, there is something causing the crash.

2. Daphnia are not low in nutritional value: Magna contain around 50% protein and monia contain around 70% protein. Daphnia also contain keratin as most freshwater inverts do, which enhances fish colors.

3. Daphnia are hard to keep indoors: Hopefully this long and extensive post proves otherwise.

4. Daphnia are hard to feed: Again, not if you know what you're doing.

5. Daphnia are very fragile and will die at the slightest hint of ammonia/nitrates: They are in fact very hardy and able to survive extreme conditions such as very depleted oxygen etc. Daphnia will slow down their reproduction if ammonia or nitrates peak, but will not die or be affected by them.

Some more pics:

I'd also like to add that I went the extra mile and raised my daphnia from lab raised diapause eggs. I only use conditioned RO water, and pharmaceutical grade spirulina (and bakery grade yeast :hihi:). Snails raised from eggs by me. Plants cultured from stems by me. This prevents many of the headaches and risks of live foods to my fish because my daphnia are relatively pure and free of parasites.

Here are some more pics:

Here are my citations and some lab studies that some people may find useful:
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2,578 Posts
I wanted to take a minute here to thank you for taking the time to post this here.

It's freakin' awesome!

But what would've made it all absolutely incredible is if you would've actually gotten the picture of your setup in there, lol!

157 Posts
Discussion Starter · #6 · (Edited)
I wanted to take a minute here to thank you for taking the time to post this here. But what would've made it all absolutely incredible is if you would've actually gotten the picture of your setup in there, lol!
Thanks! Second pic down on my last post is my set-up :) Here are some more pics:

Air Pump hooked to a gang valve

Turned off the air so you can see the daphnia. They like bunching up near the light source.

Two weeks and look how much this plant has grown from a simple stem!

My DIY Sponge Filter

Fits snugly under my desk

Great info! Thanks! I'm currently trying to keep an indoor culture alive, so this is very helpful.
Thanks! And best of luck.

How do you culture green water? What kind of fertilizers do I need to add for the algae to grow?

Also, adding floating plants will help absorb ammonia/nitrite/nitrate and keep the water clean.
I take a tablespoon of spirulina and put it in a two gallon bottle of dechlorinated tap water and keep it on a south facing window. South facing is important because this is where most of the sunlight is during the day in the northern hemisphere. Every day, I put a lid on the bottle and shake it to make sure the algae particles are suspended. Within a week I have extremely dense green water. I don't use ferts because that is a risk factor when adding to daphnia. OD of ferts will inhibit daphnia population. I don't use floating plants because they are a PITA when trying to harvest daphnia.

Nice I want to try this .... too
It's easy, go for it!

One thing I forgot to add, if your daphnia are turning clear and you want them to color up to a tannish red for your fish, increase the oxygen going into the set-up. This will instigate them to produce more hemoglobin and thus turn more tan/red. I would only recommend this method to monia and magna. Don't waste money buying Russian reds!

Here are some studies on it:

431 Posts
I am thinking of starting a Daphnia culture and wondered about the RO and remineralized water that I see commonly mentioned.

Would water collected in a tub outdoors and then pumped indoors, heated to 74f and filtered be ok? I collect rainwater for my water changes so there is no chlorine or chloramines.

Oh and the water when it was last tested in the lab had a ph of 4.6, I placed a piece of TX holey rock in the tub to balance the water chemistry nearer to neutral.

1 Posts
can you raise snails and daphnia together

Have you had any luck with raising daphinia and snails in the same container? I have a snail tank already and it would be nice for that tank to do double duty and grow daphnia as well.
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