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20L Desktop Daphnia Tank

RickyV

RickyV

Member
Joined
8 Nov 2022
Messages
231
Location
Texas
I have recently been bitten by the live food culturing bug and am currently mostly focused on daphnia. I have the outdoor Daphnia culture connected to larger system? But I decided to make an indoor culture to closely observe them in a more stable environment where I can experiment a little.

The tank is 20L. I added a small 3W pump covered in a 180 micron mesh filter bag to keep daphnia from getting sucked in. I have a little valve to reduce the flow if it does end up trapping daphnia, but it seems to be working well now. The pump brings water up to a tray filled with gravel, K1 media and some plants for nutrient removal. 20241113_111132.jpg
I added a thick layer of leaf litter to act as a slowly decomposing food source. Though it may have been too much as I am starting to see dead daphnia at the bottom. But in time the filter should begin to really help.

The daphnia tank has been a bit distracting however, I find myself looking at it much more than the reef tank across from it!20241113_111451.jpg

Here is a short video of the setup. Most of the daphnia are hanging out at the surface. Unsure if it is due to poor water quality or if they are consuming the biofilm at the surface.
 
What about yeast. That’s nice for an aquarium and easy to get

I don’t get why you would bring cow dung into the house
 
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greenbliss said:
I don’t get why you would bring cow dung into the house
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As a kid in the 1970s we had Daphnia cultures, infusoria cultures, stickleback tanks and rock pool tanks, all in a shed which had a transparent roof, our parents were a bit funny about what we brought into the house, in my case some newts escaped, poor things in my bedroom and my mate had snails and stick insects escape, the joys of parenthood in the era of proper free childhoods. As for adolescence...
 
Hi all,
For a while there was a specific strain of D. magna being sold as "russian red" daphnia
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You can cheat and <"feed them paprika"> (or carotenoids (like astaxanthin)) and they will colour up.
I know this is due to the presence of haemoglobin but it's interesting to me that daphnia and moina can apparently be productive in water with such low DO that they have to produce a lot of extra haemoglobin.
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Yes, haemoglobin, I assume that because they live in still, reasonably eutrophic water there is every chance of a low oxygen event at night etc. In <"wastewater lagoons">, where they use phytoplankton for phytoremediation, Daphnia are a real issue, because they eat the "workers" <"https://www.sciencedirect.com/science/article/pii/S2211926417302941">. They are quite interesting in <"their various different tolerances to pollution">, it is one of the reason they are <"used for bioassays">.
but I have ridiculously soft water out the tap and I've found putting some pieces of limestone scoria in my livefood cultures can make a big difference.
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Good idea, our rainwater is already <"reasonably carbonate buffered">, not ideal, but it does keep the Daphnia going.
I'm not sure how limestone would interact with a blackwater environment like this though and I'm curious if anyone has an answer. @dw1305 you seem pretty reliable for chemistry insights?
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It would depend on the dKH of the water, they don't survive in really soft water, although there are other species of Cladoceran that occur in nearly all water types. I know that if I only get Copepods or Ostracods then the water is softer and more acid <"Daphnia Culture Advice">.

cheers Darrel
 
Little said:
Would love an update on this project.
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I added some blackworms a little over a week ago, and it crashed the culture. The water got really cloudy and stinky in a few days and the daphnias were found dead at the bottom. I did a large WC and it seems to have remained clear and smell free last I saw the culture. I added a few more daphnias to the culture to restart it. I've been away from home for a week so I will see tomorrow how it is doing.
@RickyV your daphnia look very pink in that picture, is that a trick of the light or are they actually quite reddish? For a while there was a specific strain of D. magna being sold as "russian red" daphnia but I've also bought moina in the past that arrived a quite vivid red colour but where subsequent generations were clear whitish. I know this is due to the presence of haemoglobin but it's interesting to me that daphnia and moina can apparently be productive in water with such low DO that they have to produce a lot of extra haemoglobin.

Also you might not have water that makes it necessary but I have ridiculously soft water out the tap and I've found putting some pieces of limestone scoria in my livefood cultures can make a big difference. For daphnia/moina it doesn't seem to make them more productive but individual specimens seem larger and more robust.
With copepods, or whatever species of copepod I'm culturing anyway, it has a huge positive impact on fecundity as well as the size of the copepods themselves. Limestone in the water causes them to grow about three times larger, faster and even take on some colour in their carapace. The same copepods moved into a very soft water environment still manage to reproduce but much more slowly and subsequent generations are small and weak. I guess this must be because they grow more quickly and moult more often than daphnia/moina.
I'm not sure how limestone would interact with a blackwater environment like this though and I'm curious if anyone has an answer. @dw1305 you seem pretty reliable for chemistry insights?
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I recall them being quite redish. The ones I purchased were sold as regular daphnia magna. I feel the outdoor daphnia have usually been redder than the indoor ones, but ill be able to confirm tomorrow when I see them. That is good to know about the limestone. I believe in this culture I should have enough minerals as my water is on the harder side. I am curious about your copepod culturing. Ive seen a lot of the little rocket copepods in my planted tank, I believe cyclops? And I've been interested in culturing them. Can't find too much info about culturing them in FW though.
 
Because I lost all my daphnia cultures I decided I'll try something a little different this time. Moina. I started them of in a 1L container with some snails. I was giving the snails some flakes every day, and soon enough the moina population boomed without directly feeding them. I wanted to continue trying this indirect feeding in this tank now. I imagine it would be more stable in the long run with filtration. However instead of snails I will use blackworms so I can culture two live foods together.

I removed the leaf litter so I can more closely monitor the blackworms, and because I felt it wasn't nessecary. Since the moina are much smaller than the daphnia, I added a corner "overflow" using the material from a filter sock. I superglued it to the sides to keep it tight to keep anything from going into the pump chamber. It's only been a day but I am not seeing any moina getting trapped on the material which is a great sign. But I am curious how long it will last before it clogs. As you can see the blackworms are all over it so I am wondering if they will help keep it cleaner.20241227_073144.jpg
20241227_073225.jpg
Today though I did find these mystery anemone looking things. They seem to be retracting in and out. It looks like it had little babies around it. Anyone know what it is? Here's also a video so you can see how it moves.
 
Unfortunately the blackworms penetrated the superglue seams on the overflow guard. I'm thinking of just redoing it but with much more superglue this time to keep them completely away from the seams. But does anyone know of something better i can use to glue the filter to the glass? Or another better idea to keep the moina/worms isolated from the pump?
 
RickyV said:
Today though I did find these mystery anemone looking things. They seem to be retracting in and out. It looks like it had little babies around it. Anyone know what it is?
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My suspicion is that they are predating on daphnia as opposed to breeding. The family Naididae does include some carnivores like Chaetogaster diaphanus sp.
I cannot see evidence of a clitellum. A proboscis-like organ is found in Nemertia worms, but to me the structure seems very much more like acicula supporting a fan of six to eight chatea in a parapodal arrangement, and there appears to be a chaetal sac sucking this organ into the anterial or prosterial opening. There was a <similar video> uploaded on YouTube by somebody else from the states that I saw a few days ago. If it is an anterior feeding organ that is moving in and out then this is quite interesting, but equally it would be an anchor foot on the ones that you have or an adaptation to enhance respiration. More observation is needed. The parapoidal arrangement does not strike me as similar to the radial arrangement of fans on freshwater polycheate worms.
Perhaps make some detailed observations and send them to:
Dr. Robert W. Pennak
Address: 2501 E. 104th Ave., Thornton, CO 80233, USA

Or another better idea to keep the moina/worms isolated from the pump?
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I'm about to use some Fluval large breeding boxes which are pump driven. The concept is to keep tubifex in the breeding boxes and to culture something else in the tank. I was going to do pea clams, but almost anything could be mixed into the culture:

worms.png
My feeding is traditionally chlorella, bee pollen and kale powder and I am working on formulations specifically suited to different aquatic cultures. They key appears to be appreciating the value of different essential amino acids and B-vitamins found in bee pollen, the value of chlorella over spirulina, and the incredible value of kale powder in providing vitamin K. My formulation is reasonably likened to a superfood and is superior to human vitamin supplements by my reckoning, so it will be in my diet as well.

I can understand why you went for emergent plants. I think I will try water mint because that is edible, but the key is to find something that does not upset the cultures.

If you are interested, I am considering developing an enclosed acrylic culture tank developed specifically for aquatic worms? I think we have come to realise that the right product would save both money and time, and could look brilliant... but a lot can still be achieved with a bucket. By the way, boiled broccoli is all I really fed Californian blackworms and I often didn't change the water for 6 months - they don't care.

I am also darn tempted to have this design (here, right) as a fully scaped immersed tank... because worms will happily eat anything, plants grow mad with a little bit of carbon dioxide enrichment, and tubifex love the warm tropical conditions and will feed from the bottom of the trays, so it's a full cycle.
 
RickyV said:
does anyone know of something better i can use to glue the filter to the glass?
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I'm in the UK and I would use OB1 which is a modern hybrid sealant/adhesive, 100% waterproof, food-safe etc. It comes in a tube like silicone sealant. The branding will likely be different in the US but I am sure an equivalent product will be available. The only downside is it takes a while to cure. (24 hrs for full cure)

Superglue always slowly dissolves in water. Some formulations will last longer and thicker applications will last longer, but at the end of the day it will fail eventually.

Edit: Regular superglue does not stick well to glass either, which it looks like you are doing there....
 
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I decided to just go with a filter sock over the pump. Don't know why I didn't do that earlier! But the moina culture has been doing well. I have just been inconsistently throwing in yeast and trout chow to the tank and it's been doing well. Temperature is room temperature currently around 18c. Last night I added an automatic feeder with some yeast. I need to get a better one for more consistent feed but this should be good for now. I set it to sprinkle in some yeast 4 times a day. Im hoping this culture can become almost fully automatic. 20250109_113802.jpg

Plants have been doing well.20250109_113810.jpg

This morning though the daphnia were all swarming at the bottom. I'm hoping they're just hungry and it's not water quality related. Feeder should help if this is the case. Some yeast dissolves as it falls through the water column, the yeast at the bottom gets stirred up by the blackworms which feeds the daphnia and themselves.
Here is a video of the culture.
 
Safe to say the auto feeder has been working well...

I'm curious at what population they will stop growing. Or when or if they will crash. I was originally thinking of some complex photobioreactor setup to feed them but all I needed was a simple autofeeder with yeast.
 
I setup a 70L version of this culture and I noticed a big color difference in the new culture moina.
Pale moina 20250125_095711.jpg
Original pink moina
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The new culture does have a larger trickle filter and it had an airline, so I wonder if the oxygen content is what is causing this. I have heard the color is related to this but I figured I had plenty of oxygen in the 20L culture. The new culture also uses RO vs hard tap water in the original culture. But I use aragonite as the bio media in the trickle filter to add Ca/KH.
 
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Wish you was in the UK, I would love to have a small steady supply of monia.
The live food stockists here never have monia.
A few eBay sellers sell dried eggs but I’m not really up for that.
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Yeah they're pretty uncommon here in the states too. Similar to Dero worms in that they're very prolific and easy to keep yet few people culture them for some reason. I have some in 1L jars with snails by the windows and they are pretty self sustaining.
 
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