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New (and Old) Species for Live Feed - Research & Experiments


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On 6/9/2022 at 11:20 PM, nabokovfan87 said:

I will second the interest in rotifers.  I have heard of them because of my dive down trying to raise up amano shrimp in saltwater conditions but I didn't have the source of food for them.  I tried a frozen variety that didn't work, the zoeys survived for a little bit of time, but not enough. It was very likely due to me not feeding enough.  I would enjoy trying again when I have a rack.

I do have a question though.  In terms of food like this, you're breaking down protein and carbohydrate levels, which is the interesting bit for me.  What food source would be "highest protein" in the sense of lowest amount of carbohydrates?  I don't know if there is something further down the list that you'll dive into that better fits the bill for that question.  That's why I ask.

Looks like an awesome project.  Nice work.

That's hard to answer because everything depends so much on what the food source is eating. I have noticed that copepods and Daphnia pulex seems to  be consistently reported with carbs less than 10% and protein at least 60%. Any type of marine live feed seems to be even lower in carbs.

I assume your asking because fish can't process carbs? Turns out that might only be true of marine, carnivorous, and cold-water fish. Tropical omnivorous fish might actually need carbs. But I don't want to pretend like I really understand fish nutrition. This is all new to me.

I used to mass culture marine rotifers. I fed them RGComplete from Reef Nutrition with a dosing pump. Feed had to be stopped if the water started to get cloudy at all or the culture would crash.

So far the freshwater rotifers seem like the opposite. They did better when I just dumped a ton of thick greenwater grown from manure in there. But mosquito larvae got into the culture bucket and the rotifers disappeared.

Both types of rotifers seems to do a lot better in co-cultures. The marine rotifers got insanely thick after contaminating an Artemia grow out tank and so far the freshwater rotifers seem to grow thicker with Daphnia magna. 

I didn't have much time with the freshwater rotifers though so I can't say much for sure.

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On 6/10/2022 at 12:05 PM, modified lung said:

I assume your asking because fish can't process carbs? Turns out that might only be true of marine, carnivorous, and cold-water fish. Tropical omnivorous fish might actually need carbs. But I don't want to pretend like I really understand fish nutrition. This is all new to me.

In general I'm asking because of health issues with extended family, diabetes, inflammation, and ketosis type of diets as a recommendation they've been given.

We often talk about quality proteins and feeding our fish and animals high quality foods. I'm on the side of having to cook and trying to understand the "right things" to cook.  Fishkeeping is a very similar thing, I want to try to provide good food and it's an interesting topic to discuss and learn about.

You bring up an interesting point I hadn't considered, what we feed the things we are trying to eat (or feed) and the conditions and how that matters so much to the quality and end result of the products.

On 6/10/2022 at 12:05 PM, modified lung said:

So far the freshwater rotifers seem like the opposite. They did better when I just dumped a ton of thick greenwater grown from manure in there. But mosquito larvae got into the culture bucket and the rotifers disappeared.

Very interesting.  I cannot wait to have a rack, a few things to work on and side projects like this. Even having green water around would be a nice step I'd like to get towards in the very near future.

I would love to see a tour of somewhere when someone is breeding amanos on a scale. I know what's involved but they do have to maintain things like green water, rotifers, and very specific conditions to successfully raise up the zoeys.

Interesting as always, thanks for talking through it.

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On 6/10/2022 at 12:26 PM, nabokovfan87 said:

In general I'm asking because of health issues with extended family, diabetes, inflammation, and ketosis type of diets as a recommendation they've been given.

We often talk about quality proteins and feeding our fish and animals high quality foods. I'm on the side of having to cook and trying to understand the "right things" to cook.  Fishkeeping is a very similar thing, I want to try to provide good food and it's an interesting topic to discuss and learn about.

You bring up an interesting point I hadn't considered, what we feed the things we are trying to eat (or feed) and the conditions and how that matters so much to the quality and end result of the products.

Not to derail this thread too much, but I've recently become interested in culturing my own live foods & making more complete ecosystems for my fish where there are small things reproducing & feeding the large things. This interest was spurred by the decline of my betta & learning that dry foods are less than ideal for them. I've been on a path of dietary learning for the better part of 20 years. Started with switching my dogs & cats to raw food. Continued with improving my own diet due to health issues & dietary intolerances. So it was kinda a duh moment when I figured out I could to better for my fish too. 

@nabokovfan87 if you wanted to make a thread about human dietary needs & therapies in the Off-topic section, I could talk about it for days 😅

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***Freshwater Microalgae / Greenwater (1)***

The growth rate and nutritional value of a live feed often depends on the quality of the live feed's diet. For many filter feeders, such as Daphnia, greenwater is one of the best diets for both reproduction and nutrition. But the quality of the microalgae in greenwater can also vary depending on conditions and available nutrients. Not to mention greenwater cultures can be very unstable and inconsistent. 

So, what's the best and most reliable way to grow nutrient rich greenwater? 

There's a ton of research on culturing various species of microalgae. Most of them are for the biofuel industry and use different mixes of powdered chemicals as nutrient mediums that aren't very cheap or practical to use at home. I tried a few methods for growing greenwater I found on the internet but they all resulted in pale cultures. I want that thick, dark greenwater they grow for biofuel. I want the sweet green honey to ooze off …(ok, ok I'm done).

Maybe there's an easy way to mimic one of these chemical nutrient mediums with cheap, easy to find ingredients? Studies that compare different nutrient mediums consistently find a recipe called "Bold's basal medium" (BBM) to give the best growth and nutritional content. Wong 2017, for example, compared 13 different media and found BBM to be the best by a good margin.

Here's the recipe for BBM:

NaNO3: 250 (mg/L) | K2HPO4: 75 | KH2PO4: 175 | KOH: 31 |CaCl2•2H2O: 25 | MgSO4•7H2O: 75 | H2SO4: 1 | NaCl: 25 | FeSO4•7H2O: 5.0 | ZnSO4•7H2O: 8.8 | H3BO3: 11.4 | MnCl2•4H2O: 1.4 | CuSO4•5H2O: 1.6 | MoO3: 0.7 | Co(NO3)2•6H2O: 0.5 | Na2.EDTA: 50

These are the chemicals I don't want to buy. But what I already have is some fertilizer for terrestrial plants. Not surprisingly some of them have many of the same elements.

 

Replicating Bold's Basal Medium 

Here's the elemental breakdown of 1 liter of Bold's basal medium next to that of 0.34 grams of Vigoro Fruit, Nut, & Citrus in 1 liter of water – to match the amounts of nitrogen (N):

 

Major Nutrients

Vigoro + Alaska

BBM

Trace Nutrients 

Vigoro + Alaska

BBM

N

41

41

Na

 

78

P

7

53

Cl

 

28

K

26

115

Fe

0.4

1

S

10

22

Zn

0.2

2

Ca

10

7

B

0.1

2

Mg

0.2

15

Mn

 

0.4

Na

 

78

Cu

0.2

0.4

Cl

 

28

Mo

0.002

0.5

     

Co

 

0.1

 

Close ...well ...not that close. The most essential elements are boxed at the top of the list. Other medium recipes have a lot lower concentration of the trace elements, so I'm more concerned with matching the macronutrients listed in the box.

According to my local water department, my water might make up for the missing magnesium and half of the sodium and chloride but not the sulfur. However, since I'm using aged aquarium water instead of tap water, I'm not sure if that's still the case. To be sure, I can add some Epsom salt and table salt to make up all four of those elements. The differences between the rest of the trace elements I'll ignore. Hopefully the reason BBM outperforms other mediums isn't the excessive amounts of trace elements.

To make up the missing phosphorus (P) and potassium (K), I bought some Alaska Morbloom 0-10-10 NPK liquid fertilizer. 1.1 mL of Alaska Morbloom + 0.34 gram of Vigoro FN&C per 1 liter of water brings the fertilizer recipe to an almost even NPK ratio with BBM. I'll call this replication "V+A BBM".

This all might be easier to understand if we convert everything to NPK fertilizer equivalency. Unfortunately that alone wouldn't tell us much in this situation. But what might be useful is then comparing the ratio of the N to P and K values in NPK fertilizer terms. All this takes is dividing everything by the N value. This will tell us how much P and K we have relative to how much N we have.

Here's a comparison using the N:P, N:K ratios:

 

Vigoro FN&C

V+A BBM

BBM

M-8

Mod BG-11

MNM

N/N

1.0

1.0

1.0

1.0

1.0

1.0

P/N

0.4

3.0

3.0

1.3

0.3

0.8

K/N

0.7

3.2

3.4

4.0

0.6

0.6

 

I also included the NPK numbers for a few other interesting media. M-8 and modified BG-11 showed the second and third best growth in Wong's study. M-8 is especially interesting because it only includes Na, Cl, and Fe as trace elements. "Minimal nutritional medium" (MNM) was developed by Vishwakarma (2018) as the minimum ratio of NPK required to maximize Chlorella growth medium. However, the medium was developed using extremely high concentrations of nutrients (> 400 mg/L of nitrogen). I'm guessing the ratios would be the same for lower concentrations but it's possible that's not true.

 

Results

How does the Vigoro+Alaska BBM replicate stack up against the real Bold's basal medium? In the Wong (2017) paper, a maximum concentration of 5.9 mg/L of total chlorophyll was measured growing Chlorella, the most common microalgae in greenwater cultures. Plugging the optical density readings from the spectrometer at work into the equation for total chlorophyll, the V+A BBM maxed out at 5.1 mg/L. The RGB reading estimated a max of 5.6 mg/L over the weekend when I don't have access to the spectrometer. That's a lot closer than I expected.

Here's the V+A BBM graph showing the concentration of Chlorella, optical density readings, and growth per day:

480857171_Screenshot_20220610-1437222.png.be24ef7e032e43a6e09c9c3ef071da0c.png

______________

On the graph:

ChlT = total chlorophyll equation (Griffiths 2011)* read with a spectrometer (this should actually be labeled "total pigment" adjusted to mg/L dry weight of Chlorella).

R = calibration curve for difference in RGB red using the homemade colorimeter (mentioned earlier in this thread),

750nm = calibration curve for the optical density of turbidity read with a spectrometer (this can detect both live and dead microalgae cells and bacteria cells),

680nm = calibration curve for the optical density of active chlorophyll read with a spectrometer.

______________

814852566_IMG_20220531_1942427442.jpg.acc41327a1d794bf85f5d2640df72584.jpg

[V+A BBM on 6/1]

Also notice how fast the greenwater disappears after running out of nutrients? Two weeks of growth gone in less than a week. I didn't expect that. Most likely because I usually have snails or scuds in my greenwater cultures providing a slow continuous supply of at least some additional nutrients. 

621864152_IMG_20220610_1537254382.jpg.0f5a371fd6bb8727295a31773ddb08b9.jpg

[V+A BBM on 6/10]

 

Is Using Fertilizer a Bad Idea?

I've heard NPK fertilizer shouldn't be used for greenwater because excess P will build up. I don't agree this is a big problem because P is the limiting nutrient for microalgae. That means, unless you have very little nitrogen, P will be the first thing to disappear. P is also the limiting nutrient for Daphnia. Daphnids use P for protein synthesis and, if there isn't enough in their diet, they can use PO4- from the environment (Smirnov 2017). If that's not enough, putting snails in your greenwater culture will provide a continuous supply of nitrogen to ensure all of the P is consumed.

I've also heard that many fertilizers shouldn't be used because they contains copper. It's true that too much copper can be toxic to aquatic life. But copper is also an essential micronutrient for microalgae, zooplankton, shrimp and many if not most or all aquatic life. That's why copper is included in BBM and all other growth mediums that include trace elements.

 

Future Experiment 

This weekend or maybe next I'll be setting up an experiment with 6 different 1 liter greenwater cultures. All will use aged aquarium water filtered through a 1 micron filter sock and 100 mL of chlorella transferred from an established culture + different fertilizer growth medium mixes to 41 mg/L nitrogen:

Jar 1: no growth medium 

Jar 2: no growth medium + snails

Jar 3: Vigoro only

Jar 4: Vigoro only + snails

Jar 5: Vigoro + Alaska to ~NPK ratio of BBM

Jar 6: Vigoro + Alaska to ~NPK ratio of BBM + snails

__________

 

Sources:

Griffiths MJ et al. (2011). Interference by pigment in the estimation of microalgal biomass concentration by optical density. Journal of Microbiological Methods. Volume 85, Issue 2, Pages 119-123

Wong YK, Ho YH, Ho KC, Leung HM, Yung KKL (2017) Growth Medium Screening for Chlorella vulgaris Growth and Lipid Production. J Aquac Mar Biol 6(1): 00143

   *(Griffiths and Wong use different total chlorophyll equations using different wavelengths but the results come out the same).

Vishwakarma R, Dhar DW, and Pabbi S (2018) Formulation of a minimal nutritional medium for enhanced lipid productivity in Chlorella sp. and Botryococcus sp. using response surface methodology. Water Science & Technology 77(6): 1660.

Smirnov NN (2017). Physiology of the Cladocera. Elsevier Academic Press.

Edited by modified lung
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New freshwater rotifers to play with. Philodina sp.?

PXL_20220616_021527134_exported_stabilized_1655346162244.gif.fbb4b6a9e74b254a2c3327bfd7d6d625.gif

Every decent culture of freshwater rotifers so far, Brachionus or Philodina, has had a lot of these oval shaped microalgae as well. I'm not sure what they exactly are, if the rotifers are feeding on them, or if they just like the same environment.

IMG_20220518_130418328.jpg.daf09ee5cba72d5572a514dacc09e705.jpg

They seem to give the water a dark olive green to brownish tint.

PXL_20220617_003322274.NIGHT.jpg.bd501abf3cf251d04fe3c066434611f0.jpg

A large amount of them can be grown by drying freshly cut grass for a day before adding it to water. freshly cut grass without the drying will grow a more chlorella looking microalgae. If anyone has an idea of what they're called, let me know.

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  • 2 weeks later...

***Freshwater Microalgae / Greenwater (2)***

 Experiment #1 

METHOD

Volume: 1.0 L aged aquarium water.

Inoculum: 50 mL of 12 mg/L pure-ish Chlorella culture (contain some Scenedesmus).

Lighting: Feit 30-Watt PAR38 Selectable Spectrum Grow LED Light Bulb, 24 hour schedule, setting: grow.

 

Jar 1 (C): control 

Jar 2 (C+S): control + 5 snails

Jar 3 (V): 0.34 g Vigoro FN&C

Jar 4 (V+S): 0.34 g Vigoro FN&C + snails

Jar 5 (VA): 0.34 g Vigoro + 1.1 mL Alaska (1:3:3.2 N:PK ratio)

Jar 6 (VA+S): 0.34 g Vigoro + 1.1 mL Alaska (1:3:3.2 N:PK ratio) + snails

Experiment setup (6/23).PXL_20220624_012527922.jpg.bdb2f871ea7de43f72f75ac377f75c29.jpg

 

OBSERVATIONS

Controls—Chlorella remained the dominant species in both jars. However, the cultures appear a yellowish color which indicates malnourished microalgae or high bacteria counts.

Vigoro-only—Chlorella remained the dominant species in both jars for most of the first week with a small population of an unknown non-branching filamentous microalgae forming in (V+S). On day 6 the Chlorella population was largely replaced by a larger unknown motile microorganism. It is unknown if these microorganisms are feeding on or outcompeting the Chlorella. Although the filamentous microalgae in (V+S) also disappeared at the same time and ammonia is still above the API kits range which might point to outcompeting. The takeover caused the cultures to turn a faded olive green.

Vigoro+Alaska—The Chlorella population in both jars was replaced by Scenedesmus, smaller populations of a few other species, and a large populations of an unknown transparent zooplankton which could be the reason these jars lagged behind the Vigoro-only jars. By day 6 (VA) became dominated by Scenedesmus and (VA+S) became dominated by the non-branching filamentous microalgae which seems to give the culture a bright, artificial looking green color. Vigoro FN&C contains ammonia as a nitrogen source and may strongly favor the growth of Scenedesmus when phosphorus content is high enough.

Screenshot_20220626-144303.png.c0b71a4efacf73b7a42cd267321c59a4.png

Screenshot_20220626-165335.png.20b3eb5dfea7675e143341f6b02d3c00.png

 

Color comparison of the control jars (6/25).PXL_20220625_192501916.jpg.609c8916f529116af8175fa5d263c4e4.jpg

Color comparison (6/24). PXL_20220625_024330675.jpg.f1249e3a999f946f7fe157aba4661c9d.jpg

Color comparison (6/25) ~18 hours after last photo.PXL_20220625_192315991.jpg.71ede457f831ed69adb7e9f80377d83e.jpg

 

Edited by modified lung
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On 6/26/2022 at 6:23 PM, Guppysnail said:

That is crazy how fast they change. Very cool. I’m always fascinated by your cultures. I’m not extremely versed in this stuff, though I’m learning a lot through your posts. Can I ask the purpose of the snails please?

I'm basically learning this stuff as I post it too. The snails give a continuous supply of nutrients. I'm guessing their waste has some useful stuff in it besides just nitrogen. Ramshorns can handle a lot of ammonia as long as they have enough oxygen. Idk if that's true of other snails though.

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On 6/28/2022 at 10:06 PM, modified lung said:

Thanks, I'm interested to see what someone else does with them. I started feeding them to a few pygmy sunfish fry and they're doing really well too. 

Here's a thing: Ceriodaphnia Culture

I will definitely try my hand at them ASAP.  It was a cool 93’F today, so not nearly as bad as the triple digits we hit pretty much every day for the last couple weeks.

Thanks for that link!

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***Freshwater Rotifers (1)***

Bdelloids are one of the two main types of rotifers used to raise fry, the other being Monogonontas. Monogononta are much more common and have much more information available. However, I seem to find Bdelloids much more often, so I've had more opportunities to experiment with them.

GridArt_20220717_123415794.jpg.30e68d780e8a9bf21416c2117aa6b82e.jpg[Bdelloid Rotifer (left), Monogononta Rotifer (right)]

What do you feed Bdelloid rotifers? The standard recommendation is greenwater but I've rarely had success growing many this way. Turns out greenwater isn't a very good feed for rotifers …but it's also a great feed for rotifers. What I'm trying to say is rotifers are an example of why it's useful to know what exactly is in your greenwater. 

Everytime I find rotifers, I also find a population of the microalgae Scenedesmus or Desmodesmus. I wasn't sure if this was because the rotifers like to feed on this microalgae or if they just thrive in similar environments.

86357197_PXL_20220704_2002346992.jpg.169e3ff956462ca7e1f70fb318714ff5.jpg[Microalgae from the genus Scenedesmus; Desmodesmus looks mostly the same but can be found more often as a solitary cell and without spines]

Turns out it's neither. Notice in the footage below the rotifer is rejecting the Scenedesmus.

PXL_20220704_200146222_exported_1657206719239.gif.453f3a50996e1a7c32df430cc2cced6a.gif

This could be due to their spines, the size of the cell, or both. Here's an exciting video I recorded of rotifers trying to feed while surrounded by Scenedesmus:

https://youtu.be/L9Dfy_7XfAg

[How do I embed videos on here?]

At a few points in the video you can see the rotifer occasionally accept either a solitary cell of Scenedesmus/Desmodesmus or more often cells of what looks like the microalgae genus Chlorella which are less than 25% the size.

1451027619_PXL_20220706_0147167912.jpg.29149b484f1298ef0fc681331c585e99.jpg[Microalgae from the genus Chlorella]

This might be why freshwater rotifers are considered so hard to culture. If you feed them greenwater, they'll filter out only their preferred type of microalgae (like Chlorella) from the greenwater. Once those are gone, the unprefered type (like Scenedesmus) will take over leaving little for the rotifers to feed on. The whole time, the culture stays green in color which can easily lead you to believe the rotifers still have plenty to feed on. But in reality, they're starving and the culture crashes.

Now that I've wasted your time on that, Bdelloid rotifers do better on yeast and bacteria than microalgae (Ricci 1984), higher densities were achieved by feeding water used to wash rice and potatoes (Hayashi 1992), and faster reproduction was observed on a diet of flour than on Chlorella or bacteria (He 2022). 

But maybe not such a waste of time. Using things like yeast, flour, and vegetable wash tends to foul the water quickly. Ammonia may not be a big issue for rotifers. The thickest population I currently have is growing in a Chlorella culture with about 15 ppm NH3/NH4+. But the smell of fouled rotifer water might not be particularly thrilling at home …especially to your spouse …I'm told.

And constant water changes aren't all that easy with something as small as rotifers. Not that it's impossible, just more difficult.

Greenwater, however, is easy. I get a ~99% pure Chlorella culture just by pouring  greenwater through a cheap 1 micron filter sock (2–4 micron would probably work too). Add a pinch of NPK fertilizer or manure and wait for it to darken. With one of my recent Chlorella cultures, the rotifers just appeared in the jar on their own after 2 weeks. Did you know that some people sanitize their equipment? Lol!

 

Sources 

Hayashi N, Inamori Y, Sudo R (1992). Mass culture of small metazoa philodina erythrophthalma isolated from a wastewater treatment process. Yuyo bisho kosei dobutsu wamushirui Philodina erythrophthalma no baioriakuta eno teichakuka no tameno komitsudo baiyoho ni kansuru kenkyu." Japan.

He Y, Liu J, Shen C (2022). Innovative method of culturing bdelloid rotifers for the application of wastewater biological treatment. Front. Environ. Sci. Eng. 16, 43.

Ricci C (1984). Culturing of some bdelloid rotifers. Hydrobiologia 112, 45-51.

Edited by modified lung
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On 7/9/2022 at 3:59 PM, modified lung said:

I bought mine from AmScope for $80. Totally worth it.

There is currently a sale happening on AmScope🧐 including a sale on the image conversion eye piece (on any scope with multiple eye-pieces, so the eye piece is removable, a USB conversion to record and put on the computer screen)

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***Freshwater Rotifers (2)*** 

Possible breakthrough with freshwater rotifers. 

Thinking about feed size most of the information out there is about Monogononta rotifers. At least one paper I found reported negative population growth for a Monogononta rotifer when fed Scenedesmus microalgae and found a species of Chlorella to be the most ideal microalgae (Abou-Shanab 2016). This is what I've seen with my home cultures as well [see my last post about rotifers here].

Rothhaupt (1990) found that various species fed best on different sizes of microalgae which mostly depended on the rotifer's body size. Most species preferred microalgae between 6 and 12 microns in diameter. For reference, Chlorella is between 2 and 10 microns in diameter and Scenedesmus, which was being rejected by my Bdelloid rotifers, is oval shaped with a length of between 13 and 20 microns.

This other paper, which I could only find the abstract, backs up the same idea with a Bdelloid rotifer which preferred particles of flour less than 10 microns wide.

This abstract of an undergrad poster presentation was interesting. It claims that a Monogononta rotifer fed much slower on large particle sizes than on smaller sizes. But when sizes are mixed, the feeding rate on the smaller particles reduced to the slower rate of the larger particles. So mixing different sizes of microalgae may not be ideal which is unfortunate because Scenedesmus grows fast and easy. So far I haven't been able to keep it from getting into any of my greenwater cultures.

So what's a small sized feed suitable for rotifers that's easy and won't foul the water? Bacteria.

I induced a bacteria bloom in a pickle jar rotifer culture by adding a dab of molasses. The jar already had a small population of Bdelloid rotifers, a smaller population of Monogononta rotifers, and an almost exhausted population of Chlorella. 48 hours later, the bloom cleared and the population of Monogononta rotifers increased by 50 to 100 times

This gif shows only part of a single drop of water from the culture: PXL_20220716_173304102_exported_1658086107983.gif.308486ce628e0a2367f486c8fa0a0b15.gif

It seems like bacteria alone usually isn't a suitable diet for most filter feeders, so I'm assuming some greenwater in the culture is still necessary. I have another jar started with no greenwater supplement to test this out.

Either way, enough Chlorella is easy to filter out from greenwater. I found just a coffee filter will let through Chlorella with only the smallest maybe 80% of Scenedesmus which isn't that bad.

Hopefully this is a sustainable way to grow freshwater rotifers. I'll let you know how it's going next mont.

 

Sources

Abou-Shanab RAI et al. (2016) Effect of Brachionus rubens on the growth characteristics of various species of microalgae. Biotechnol. vol.19 no.4

Rothhaupt KO (1990). Differences in particle size-dependent feeding efficiencies of closely related rotifer species. Limnol. OctBanogr.. 35(l), 16-23.

 

Edited by modified lung
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Holy mother of ducks, I put only 4 rotifers and a dab of molasses in this jar not 24 hours ago. Not all of these are rotifers though.

PXL_20220718_004258676_exported_1658108276721.gif.345285fc75df8caa13b0de09de72879c.gif

PXL_20220718_004427921_exported_1658108355197.gif.889176e7bebc8af1fd13816b0d01e7e7.gif

Monogononta rotifer, hundreds of them already.

PXL_20220718_005231284_exported_1658107182667.jpg.9c8ccfa6f782411b600c59f26cb8ff3f.jpg

Ciliates, genus Oxytricha? I see these really often but not in this number. These are some of what we like to call "infusaria"

PXL_20220718_005020047_exported_1658108415877.gif.c620c2f1426ba603e16173c649f9cc02.gif

No idea what these are.

PXL_20220718_005419437.jpg.e7725f8b75db94e2dc768c0cf412a19d.jpg

There's also a few Bdelloid rotifers and paramecium.

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  • 1 month later...

***Chydorus (1)***

I've been trying to establish a growing population of Chydorus for a while and finally made some progress.

My first attempts to culture Chydorus were to use the same methods for culturing Daphnia—just add greenwater. But these would always eventually die out. Luckily I could always find a few new Chyds (I'm going to call them Chyds) in the detritus of my Ceriodaphnia cultures to try again.

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Looking through the literature, Vijverberg (1997) found that Chyds grow much better in small scale cultures when fed natural lake detritus than with a microalgae (greenwater) mix of Chlamydomonas and Scenedesmus. Also, in natural waters where Chydorus populations are the most abundant zooplankton, the amount of suspended [in the water column] microalgae also tends to be highest—which is generally considered to mean it's not being fed upon (Eyto 2001). The largest populations of Chydorus are found in still pools or ponds where their main food source seems to be detritus and periphyton—algae and bacteria that grows on the surface of aquatic plants, wood, or debris (Basińska 2014).

All of this together is interesting. First, it sounds like Chyds prefer grazing over filter feeding which might be why suspended microalgae is abundant where Chyds are also abundant. But we can also look at it a different way. Maybe Chyds are abundant where suspended microalgae is abundant. That might sound redundant but what I mean by that is "maybe the causal factor isn't as intuitive as we might think?" 

Most Daphnids that rely primarily on filter feeding actually suffer when suspended microalgae becomes too dense (Smirnov 2017). But that density shouldn't matter to grazers. And when suspended microalgae is dense, much of it settles. Settled microalgae can be grazed on. So lots of suspended microalgae could mean less competition from filter feeders which means more settling for the Chyds to feed on.

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My experiments seem to confirm this. The Chyd population at the bottom of my detritus filled Ceriodaphnia tank always stayed extremely small. But my first successful Chydorus cultures came from allowing microalgae to settle in low light conditions in vials about the size of a camera film canister (I keep my film canisters right next to my rotary dial landline). Under the microscope their guts appear green or bright yellow which I believe means they are indeed feeding on both living and dying microalgae.

The type of microalgae so far doesn't seem to matter. Maybe cell size isn't a limiting factor for grazers like it is for filter feeders. In fact, so far I've found using a microalgae with a larger cell, like Scenedesmus, works better because it prevents contamination by  copepods.

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It also seems like Chydorus is the only thing I've come across that can utilize non-branching filamentous (nbf) microalgae as a food source—possibly due to the grazing. In the photo above, the jar on the left is pure Scenedesmus and the jar on the right is mostly an unidentified nbf. The population of Chyds in each looks about the same.

 

Feeding My Fry

My cultures haven't grown dense enough yet to test adding Chydorus as a major part of my frys' diet. I also can't find records of anyone else doing so. This is surprising because Chyds have been found to be a major part of wild fry diets, have among the highest potential protein content I've seen at over 70% (although high protein isn't everything), and adults are about the size of newly hatched brine shrimp.

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Adding a supplemental feed would probably increase my output. I found one record of culturing Chyds at high density (EPA-660/3-75-010 1975). They fed small amounts of LIV (a dehydrated egg product?), cerophyl (wheatgrass extract?), and brewers yeast three times a week. But I don't much like using yeast and I'm not sure what those other two things are exactly. But others have found Chydus populations increase faster in the presence of Daphnia, midge fly, and snail feces (Smirnov 2017). First I'll test adding some cow manure and see what happens from there.

 

SOURCES

Smirnov NN (2017). Physiology of the Cladocera. Elsevier Academic Press.

Belyaeva M, Deneke R (2007). Colonization of acidic mining lakes: Chydorus sphaericus and other Cladocera within a dynamic horizontal pH gradient (pH 3−7) in Lake Senftenberger See (Germany). Hydrobiologia volume 594:97–108.

Elvira de Eyto (2001) Chydorus sphaericus as a biological indicator of water quality in lakes, Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen, 27:6, 3358-3362,

Vijverberg J & Boersma M (1997). Long-term dynamics of small-bodied and large-bodied cladocerans during the eutrophication of a shallow reservoir, with special attention for Chydorus sphaericus. Hydrobiologia 360: 233–242.

Basińska AM, Antczak M, Świdnicki K, Jassey VEJ, and Kuczyńska-Kippen N (2014). Habitat type as strongest predictor of the body size distribution of Chydorus sphaericus (O. F. Müller) in small water bodies. International Review of Hydrobiology 99: 1–11.

Martin DB, Novotny JF (1975). Studies to determine methods for culturing three freshwater zooplankton species. EPA-660/3-75-010.

 

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On 8/19/2022 at 10:57 AM, modified lung said:

vials about the size of a camera film canister (I keep my film canisters right next to my rotary dial landline)

I laughed out loud at this. The kids would say LOL'd 

I've gotta get some cultures going. I find this all absolutely fascinating. Thank you for sharing it with us!

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On 8/19/2022 at 1:37 PM, eatyourpeas said:

Loving this journal! Thank you so much for sharing all the information, @modified lung😍

 

On 8/19/2022 at 3:34 PM, Anjum said:

I laughed out loud at this. The kids would say LOL'd 

I've gotta get some cultures going. I find this all absolutely fascinating. Thank you for sharing it with us!

Thanks, journalling on here helps me remember what I've done. 

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  • 2 weeks later...

I found an infusaria-like swarm of green specks in my bacteria fed rotifer jar. Possibly "green paramecium" which according to my secret sources (Google) has a symbiotic relationship with a "chlorella-like algae". No idea if this is a viable food source but it's different and different is cool.

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Edited by modified lung
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  • 1 month later...

***Chydorus (2)*** 

At a crazy 70% protein and an adult size smaller than newly hatched brine shrimp, chydorus has been one of the main new live feeds I've been trying to develop a low maintenance, high density culture method for. 

I made some progress feeding microalgae that had settled on the bottom of culture jars so the chydorus could graze on it rather than filter. After finding some literature that suggested feces was important to chydorus reproduction, I tried using cow manure. But results from both of these were inconsistent.

More progress came after noticing the population grew faster when the jar was kept away from light. However this only seemed to be true in the jars fed microalgae. Regardless, the population never grew large enough to support regular harvesting.

At this point it's been about 8 months of trial and not quite good enough results ...then I discovered I already had a super high density chydorus culture. They were in my 55 gallon scud barrel probably this whole time.

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I usually skim duckweed off the surface with a net that can let the smallest scuds through. Last week a different kind of duckweed took over. It's much smaller and almost spherical so I used a much finer net. Wondering what kind of duckweed this could be, I put the net in a bucket of water. The next day, I found thousands of chydorus in the bucket.

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ALL THE WASTED TIME AND EFFORT!!

But still I want to figure out how to grow them in jar indoors. So what could they be eating in the barrel that allowed their population to grow to large? The barrel has hundreds, maybe thousands, of scuds whose only food source is dead plant matter mostly from hornwort and elodea. Maybe the chydorus are eating the same thing.

This would make sense of the low light jars with microalgae. Perhaps it was the low light causing the microalgae to die off which made for a better food source than living microalgae. 

I decided to throw in a few different types of leaves from a spring mix salad and compare that to jars fed spirulina powder, golden pearls fry food, and live greenwater. Of the three feeds I just mentioned, there was no noticeable difference in population size, although they all did sustain the population. Thicker leaves from the salad mix, like spinach and swiss char, turned the water cloudy very quickly, killed off the chydorus, and filled with infusaria over the next two days.

But jars fed thinner, more fragile types of lettuce had a big population boom. Other thin leaves, like celery leaves, also worked well. Yellowing leaves were consumed almost completely over night. Thin, dying plant matter seems to be the secret.

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Edited by modified lung
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