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

[modified lung]

Because I like to collect from the wild, I come across a lot of Interesting zooplankton. Generally, I discard the ones I can't identify as a viable food source and feed the ones I can to my fish. 

In the past, I haven't put much effort into keeping any of these zooplankton. Because they're collected from the wild, any culture tends to become contaminated with numerous known and unknown microorganisms. Without closely monitoring what's growing in them, you're not really sure what you're feeding your fish. Well all that's about to change because daddy bought a microscope ... that's me …. I'm daddy.

So, for the past few weeks I've been doing a lot of digging for information on some of these zooplankton, mostly various types of water fleas, and thought I'd share some of it. 

First, note that I've listed the higher percentages of nutrional content I've found. The nutritional content of zooplankton can vary by a large degree depending on the quality of their food source. For example, I found reports of the % protein of Daphnia magna to be anywhere between 42–62%. The quality of the food for water fleas, with the exception of Bosmina, seems to be based on it's phosphorus content which is their limiting nutrient. 

The quantity of food is also important. Water fleas increase their filtering rate when food is scarce. When exposed to prolonged periods of low feed concentrations, the increased filtering rate can use more energy than they receive from their food resulting in nutrient deficiencies or even death by starvation.

Too much food can have a similar effect. Water fleas slow filtering rates when food is abundant, but they also increase grooming activity. When feed concentrations are too high, grooming can speed up to a rate that also uses more energy than the water flea can receive from their food.

...Anyways  here are some of the interesting zooplankton I've found:

Bosmina longirostris

Length: 0.2–0.6 mm

60% protein, 18% lipid, 12% carbohydrates, 6% ash, 4.8 kcal/g

Found clinging to plants and detritus. Confirmed food sources in the wild include phytoplankton, bacteria, protozoans  detritus, and feces. Can both filter feed and graze particles from surfaces.

Mass cultures are rare but have been successful using phytoplankton, snail feces, and animal manure.

Chydorus sphaericus

Length: 0.3–0.6 mm

70% protein, 19% lipid, 8% carbohydrates, 3% ash, 6.1 kcal/g

Found clinging to plants, detritus, and suspended in open water. Tolerant of an extremely wide range of water parameters.  Confirmed food sources in the wild include phytoplankton, protozoans, bacteria, and detritus. Midge fly larvae feces has been reported to be important for reproduction. Chydorus is often found to be the major food source of wild fish larvae.

Mass cultures are rare but have been successful using phytoplankton and a mixture of yeast, powdered trout feed, and cerophyl (wheatgrass vitamin supplement).

Ceriodaphnia dubia

Length: 0.4–1.2 mm

54% protein, 12% lipid, 30% carbohydrates, 4% ash, 4.9 kcal/g

Found suspended in open water in a way very similar to Daphnia. Confirmed food sources in the wild include phytoplankton and suspended bacteria. Ceriodaphnia are commonly used in toxicity studies and are considered a water quality indicator species by the EPA. 

Mass cultures have been successful using yeast, powdered trout feed, and animal manure. Cerophyl has been successful as a feed in soft water to medium hard water only. Mixed species of phytoplankton have been successful but isolates of many single phytoplankton species have not.

Ceriodaphnia have the highest feeding rates in lowlight conditions but stop feeding in the dark. Multiple daily peaks in feeding rates can be induced with exposure to multiple high/low light cycles a day. Ceriodaphnia also do much better under low feed conditions than most other water fleas.

Daphnia magna

Length: 1.5–4.5 mm

62% protein, 9% lipid, 22% carbohydrates, 7% ash, 2.5–5.6 kcal/g

Found suspended in open water also in a way very similar to Daphnia ...because they are Daphnia. Confirmed food sources in the wild include phytoplankton, suspended bacteria, cyanobacteria, detritus, feces, and even inorganic forms of nutrients such as phosphate when organic forms are unavailable.

Mass cultures have been successful using yeast, phytoplankton, animal manure, and waste products from food processing plants or powdered forms of soybean, green pea, and rice bran. Daphnia fed yeast were found to have the much higher nutritional content but much lower growth and reproduction rates compared to daphnia fed phytoplankton.

Cyanobacteria fed cultures have similar reproduction rates to phytoplankton diets but only after an intial die off and adaptation period. Daphnia cannot survive on pure bacteria diets but can achieve bery rapid growth and reproduction rates on 50/50 to 80/20 ratio phytoplankton/bacteria diets. Cultures using mixed diets always outperform pure diets.

Daphnids do 85% of their feeding in the hours surrounding sunrise and sunset. Feeding rates are moderate during daylight periods and slows dramatically around midnight.

Moina macrocopa

WHY CAN'T I FIND YOU?!?!

Here's some info anyways...

 

Length: 0.6–1.8 mm

63% protein, 18% lipid, 18% carbohydrates, 1% ash, 4.0–4.3 kcal/g

Confirmed food sources in the wild are similar to that of Daphnia magna.

Moina has been successfully mass cultured with the same feeds as Daphnia. Moina however can be fed fish and canola oils, a higher percentage of suspended bacteria, and cyanobacteria without the initial die off.

Moina is being seriously tested by some hatcheries as a full replacement for baby brine shrimp which has resulted in higher reported fry survival rates. This may be because Moina contains higher levels of a few very important essential nutrients for many fish larvae than BBS.

Simocephalus vetulus

Length: 0.6–2.6 mm

54% protein, 12% lipid, 30% carbohydrates, 4% ash, 3.7–4.0 kcal/g

Found clinging to solid objects, especially vegetation. Confirmed to feed on phytoplankton, bacteria, protozoans, and detritus. Can feed by filtration or by scraping algal or bacterial growth off the surface of objects. Bacteria can play a major dietary role. Simocephalus feeding rates are not affected by light levels.

Mass cultures have been successful using phytoplankton and biofloc.

Brachionus rubens (Freshwater rotifer)

[The numbers below are from a non-specific rotifer species]

Length: 0.2–0.3 mm

52% protein, 26% lipid, 18% carbohydrates, 5% ash

Found in open water, clinging to surfaces or to larger zooplankton such as Daphnia magna.

Mass culture has been successful using phytoplankton and yeast.

____________

That's it for now. In the future I'll share some culture techniques and experiments  I'm doing for each of these and with greenwater. More species might be added if found.

Sources either directly from or from the reference sections of:

Physiology of the Cladocera by Nikolai N. Smirnov

Plankton of Inland Waters by Gene E. Likens

Ecology and Classification of North American Freshwater Invertebrates by Thorp and Covich

Moreau A, Dupuy C, Bocher P, Farau S (2021) Morphological, calorific and nutritive characteristics of 656 freshwater invertebrates taxa. Biodiversity Data Journal 9: e70214

Edited August 30, 2022 by modified lung
Added journal links

[Guppysnail]

This is fantastic.  Microscopes in this hobby are very fun and useful.  Thank you for sharing all this research it’s amazing.  ORD 😍 🏆 

Edited May 5, 2022 by Guppysnail

[Torrey]

These photos are great!!!!

I wonder if we'll ever get to the point we can just order some daphnia magna or moina to tackle cyanobacteria in the tank?

[Torrey]

I miss having a microscope, looking at hacks on how to turn a cellphone camera into a microscope😁

[modified lung]

On 5/7/2022 at 10:11 PM, Torrey said:

I miss having a microscope, looking at hacks on how to turn a cellphone camera into a microscope😁

I just got an $80 one from AmScope. Works surprisingly well.

[Lowells Fish Lab]

Love this. It's always somewhere in the back of my mind that there are likely many more microfauna that could be cultured as a food source than we typically talk about. I have a tank that occasionally blooms large populations of what I think are tetrahymena. They're just large enough to be seen with the naked eye and from what I've read are easy to culture in large numbers. I wonder if it could work as a general purpose infusoria solution instead of paramecia.

[modified lung]

***Smartphone Colorimetry to Measure Greenwater Concentration (1)***

Since overfeeding is a major factor in zooplankton (Daphnia, Moina, etc.) culture crashes, one of the experiments I'm planning for the near future is to find how much greenwater is too much greenwater? But to do this I need a way to estimate the concentration of greenwater per volume of water I'm adding to each culture.

And because I like making things as hard as possible on myself, I'll be doing it while spending as little money as possible on the tools typically required for the job. So for the past few weeks I've been working on a DIY RGB colorimeter to measure optical density and finally found a working configuration that gives consistent results: 

It's made from 2 empty test strip bottles, one test strip bottle cap, black duct tape, black construction paper, red post-it note paper, a rubber spacer thing, a LED flashlight, and an API liquid test kit test tube. Here's a picture of it disassembled: 

Concentrations can be determined by shining a colored light through a liquid solution of it's complementary color and measuring how much of the colored light is blocked.

You can read more about this here: (PDF download).

In the case of greenwater the solution is green, so the light needs to be red. The red paper acts as both a light filter and a light diffuser that evens out the shade of red when shined through a vial.

The color detector, a smartphone camera running the Color Grab app on Android, can then determine a concentration by comparing the amount of red light that is blocked by a vial of greenwater to the amount of red blocked by a vial of clear water (the blank). The bigger the difference the more concentrated the green. Add some mathematical voodoo and we can figure out the concentration of phytoplankton.

Here's a screenshot of the app reading the blank vial:

 

Spreadsheet Gibberish

Time to glaze your eyes over. 

To confirm accuracy, I ran the some samples and dilutions of greenwater through the spectrometer at work, then through the DIY colorimeter, then ran the results through some spreadsheet equations. Here are the results from last three samples:

The "Spectral Absorbance" section is the absorbance readings from the spectrometer.

The "RGB Absorbance" section is the readings from the colorimeter converted to absorbance (-log[sample/blank]). 

In the "Concentration" section the grey cells are the spectrometer readings ran through the equations from Griffiths 2011. The density is the concentration of chlorophyll and carotenoid (peak nm) adjusted for turbidity. But take these concentration numbers with a big grain of salt. The specific equation was meant for pure Chlorella cultures and I'm not using a pure culture.

Also I couldn't find any clear examples of equation like these being used, so I'm only 90% sure I'm using it correctly. Papers like these tend to be very vague on the math because they assume the reader is already familiar. Helpful.

Either way, I'll have to order some super fine filter cloth to perform dry weight measurements and develop a concentration curve to be sure. Absorbance values are enough but it would be nice to translate them into a metric that makes more sense.

The light green spreadsheet cells are the red (R) and RGB with blue adjusted by *1/3 (RG[B*x]) absorbance values ran through the Griffith equation.

The dark green cells are the same R and RGB absorbance values ran through Beer's Law. This is the important one.

As you can see the RG(B*x) colorimeter results consistently line up with those from the spectrometer ...at least in a way I'd describe as "close enough". This ain't no fancy lab with a sweet budget after all.

As a last note, according to Griffiths 2011, using optical density to measure phytoplankton density has a very large error rate because the concentration of chlorophyll, which is mostly what's being measured here, can vary greatly depending on the health of the culture. For our purpose I don't see this as a problem because the health of the culture is related to the nutritional content of the phytoplankton which is related to part of the reason Daphnia cultures might crash from overfeeding (energy spent filtering > energy received filtering). So I don't see why the optical density can't be used as a rough measurement of nutritional concentration of the phytoplankton culture. That's what really matters here after all.

 

Well that was good fun. Now what new thing should I obsess over for the next few weeks? I'm going to try and make a DIY spectrometer at some point. And next Friday I'll be getting in a few dry powder feeds to compare feeding to my zooplankton cultures.

 

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

Edited August 18, 2022 by modified lung

[Torrey]

On 5/14/2022 at 8:48 PM, modified lung said:

Also I couldn't find any clear examples of equation like these being used, so I'm only 90% sure I'm using it correctly. Papers like these tend to be very vague on the math because they assume the reader is already familiar. Helpful.

One of my greatest delights was finding out I could use the "contact" option in most peer-reviewed journals to ask questions about specific parameters in hopes of replicating experiments which then increases validity of the original experiment (for anyone still reading along). Email geeking ensued, and even though I never got permission from the university to actually duplicate an already peer-reviewed experiment, I did learn from the original research teams how to ask for more data, how they arrived at the data, and that they actually get pretty excited when somebody fans their work and asks for details not covered/explained well in the paper. 

[modified lung]

***Ceriodaphnia (1)***

Is it worth culturing Ceriodaphnia? I found 4 studies that tested Ceriodaphnia diets for larval fish.

Study #1 (Patra & Ghosh 2015) compared feeding Artemia, Rotifer, Moina, Ceriodaphnia, egg custard, and greenwater to angelfish (Pterophyllum scalare) for the first 20 days. Survival rates were as follows: Artemia: 75%, Rotifer: 68%, Moina: 71%, Ceriodaphnia: 29%, Egg custard: 31%, Greenwater: 24%. 

Study #2 (Farhadian 2012) fed Mayan cichlids (Cichlasoma urophthalmus) starting at 5 weeks and 10 weeks old with a survival rate of 97% and 100%. This paper also discusses the nutritional value of Ceriodaphnia and noted those grown on greenwater had the best nutritional content. These contained 54% dry weight protein, 12% lipid.

Ceriodaphnia also have much higher 18:2n-6 and about equal 18:3n-3 essential fatty acids, both of which are considered the most important for general fry growth and survival, when compared to Artemia, Daphnia, and Moina. 

(Ceriodaphnia culture in a half gallon jar)

Study #3 (Akintola 2009) looked at the growth and survival of hybrid African catfish (Clarias gariepinus x Heterobranchus bidorsalis) on live Artemia, decapsulated Artemia cysts, Ceriodaphnia, and a 50% protein commercial diet for 28 days. The highest survival rate was on decapsulated cysts (95%) followed by Ceriodaphnia (85%). Growth rates followed the same order. The lowest in both parameters was the commercial diet. The paper notes that many fish don't have the enzymes necessary to digest artificial diets during the larval stage which is likely why the commercial diet performed the worst.

Study #4 (Ajepe 2014) also looked at two species of African catfish and their hybrid (Clarias gariepinus and Heterobranchus bidorsalis). This study compared growth and survival when fed live Artemia or Ceriodaphnia as a first food for 21 days. Ceriodaphnia had the higher survival rate (95-97%) compared to Artemia (72-91%).

According to this paper, growth rates are generally thought to be dependent on feed protein level. But Ceriodaphnia had the higher growth rates despite Artemia having a protein content of 63% compared to the Ceriodaphnia with 58%. However, the paper goes on to explain that many species have a maximum threshold where increased protein content no longer increases growth rates which is likely why the growth on the Ceriodaphnia diet outpaced those on Artemia. Even more, exceeding the threshold by a significant amount can also have a negative effect on growth rates.

-----------------

It seems whether or not Ceriodaphnia is a good live feed depends on the species of fish. But all the above studies fed pure diets of each live feed. The aquaculture industry likes to think there's a silver bullet live feed out there that can be fed to fish as the only food source. In my opinion, this is unrealistic and fish should always be fed mixed diets to maximize growth, health, and survival.

So the above studies are of limited usefulness because the question shouldn't be "is Ceriodaphnia an adequate diet?" but instead "can Ceriodaphnia be a good part of the diet?" To me, a live feed is considered "good" if it (1) contributes positively to the survival, growth and health of the fish and (2) culturing it requires me to leave the couch as little as possible. Ceriodaphnia meets both of these.

Feeding My Fry

I added Ceriodaphnia to the diet of my CPD and ricefish fry about 4 months ago. Since then, my survival rates with both species have noticeably increased to the point that I need to add another grow out tank.

The fry also receive infusaria, vinegar eels, and some powder feed. Before Ceriodaphnia, their diet also included newly hatched brine shrimp. But I really dislike hatching brine shrimp. With the addition of Ceriodaphnia, I've been able to completely remove brine shrimp from my fry's diet with better results. In fact, last week I sold off all my cans of unhatched cysts.

I think the improvement comes from the fact that brine shrimp can only live in freshwater for about an hour. Ceriodaphnia, however, survive until they are found and eaten by the fry which means both more food and better water quality for the fry. 

If the fry are too small to eat adult Ceriodaphnia, I still leave a population of adults in the fry tank. Adding greenwater to the fry tank every couple days keeps the adults continually reproducing. Much like Daphnia, when conditions are good, Ceriodaphnia give live birth to offspring. The newborn offspring are much smaller than newly hatched brine shrimp and can be eaten by the smallest fry.

(Ceriodaphnia culture in a 5 gallon tank)

Culturing Ceriodaphnia

Culturing Ceriodaphnia is insanely easy. All they need is a cup of greenwater every few days to keep the population growing steadily. They can survive on extremely low concentrations of food, much lower than Daphnia. I've skipped feeding them for a week with little noticeable reduction in population. Skipping feed for Daphnia for the same amount of time results in a big die-off. Adding pinch of Spirulina powder to the Ceriodaphnia culture seems to triple the adult population over a few days and I'm yet to have a culture crash.

 

Sources

Patra S & Ghosh TK (2015). Larval rearing of freshwater Angelfish (Pterophyllum scalare) fed on different diets. IOSR-JAVS. Volume 8, Issue 6 Ver. I. PP 06-11

Farhadian O et al. (2012). Culture Experiments With A Freshwater Cladoceran, Ceriodaphnia quadrangula (O. F. Müller, 1785), As Suitable Live Food For Mayan Cichlid (Cichlasoma Urophthalmus Günther 1862) Larvae. Braz. J. Aquat. Sci. Technol., 16(2):1-11.

Adewolu MA et al (2009). Growth performance and survival of hybrid African catfish larvae (Clarias gariepinus x Heterobranchus bidorsalis. The Zoologist Vol. 7: 45-51.

Ajepe RF et al  (2014). Comparative Study of Artemia (Brine Shrimp) and Ceriodaphnia (Zooplankton) as Foods for Catfish Larvae. American Journal of Experimental Agriculture, 4(7): 857-865.

 

Edited August 18, 2022 by modified lung

[Guppysnail]

This is awesome.  Thank you for sharing. Including these will be very helpful for both my new hatch CPD and Pygmy cory fry. They are both to small for brine shrimp. The baby Ceriodaphnia sound like just the right size. 
 

I am also totally on board with this!😍

On 5/31/2022 at 7:43 PM, modified lung said:

2) culturing it requires me to leave the couch as little as possible. Ceriodaphnia meets both of these.

 

[modified lung]

@Guppysnail NP. I found my first ones in a pond. They seem to be found anywhere daphnia are. But they seem to be on the opposite boom-and-bust schedule. When the daphnia disappear, the ceriodaphnia population explodes. Then they disappear when the daphnia comes back.

Edited June 1, 2022 by modified lung

[Torrey]

On 5/31/2022 at 6:04 PM, Guppysnail said:

This is awesome.  Thank you for sharing. Including these will be very helpful for both my new hatch CPD and Pygmy cory fry. They are both to small for brine shrimp. The baby Ceriodaphnia sound like just the right size. 
 

I am also totally on board with this!😍

 

I was thinking of you the entire time I was reading this!

I'm betting @Fish Folk would like to get a culture going too.

On 5/31/2022 at 9:02 PM, modified lung said:

they seem to be on the opposite boom-and-bust schedule. When the daphnia disappear, the ceriodaphnia population explodes. Then they disappear when the daphnia comes back.

Almost sounds like they live in pretty close relationship to each other, maybe worth growing them together in a tank with aged water and see if you can find a homeostasis mark?

Would definitely be interesting to see if getting an aged, established, well seasoned and planted tank supporting a good colony of these, and then introducing a few breeders. I wonder if a growing population of ceriodaphnia might be one of the "missing links" in triggering spawns? Like, in the wild, what are the chances that fish fry who did really well with these... their parents spawn when the population starts increasing, knowing that when it starts to shrink the larger daphnia population will begin to grow?

[Guppysnail]

On 6/1/2022 at 12:51 AM, Torrey said:

one of the "missing links" in triggering spawns?

A few years ago on either a discovery or animal planet channel I seen a documentary on wild fish. I cannot remember which fish but it is not a hobby fish. I was just randomly half watching. Whatever type of fish they were documenting would not spawn no matter how plentiful food was until a certain microfauna (the type their fry ate most) season started. Once that fauna flourished it was the spawning trigger.  Apparently something humans were doing was causing an extreme decrease in this fauna and it was threatening populations of the fish from reduced spawning. 
 

From all that I now feed micro fry foods to tanks I’m trying to encourage spawning even with no fry present. It “seems” to do the trick.  Though it could be just coincidence or the extra food for adults to munch but since I started doing it I have not had trouble encouraging spawning in any fish type. 

Edited June 1, 2022 by Guppysnail

[modified lung]

On 5/31/2022 at 9:51 PM, Torrey said:

Almost sounds like they live in pretty close relationship to each other, maybe worth growing them together in a tank with aged water and see if you can find a homeostasis mark?

Whenever I have a daphnia culture crash and stop putting food in the bucket, it's always taken over by cerio a week later. Idk what they're eating during that week.

There's always a few daphnia in my cerio cultures but they've never taken over. I suppose you'd have to find a balance where the food's not so high the daphnia out reproduce the cerio but not so low they starve to death filtering nothing.

On 6/1/2022 at 2:58 AM, Guppysnail said:

From all that I now feed micro fry foods to tanks I’m trying to encourage spawning even with no fry present.

That's really interesting. I feed fry food to my spawning tanks too. But I do it just in case there are fry I don't know are there. I never considered it might trigger the spawning. That could actually explain a few things with my rosy loaches.

[Odd Duck]

So where would I find a Ceriodaphnia culture?  Are they commercially available or do I need to grub around in some mucky ponds and get covered with mosquito bites?  Cuz I’m a mosquito magnet and my knees are well past the hiking stage.  😝 

[modified lung]

On 6/2/2022 at 3:27 AM, Odd Duck said:

So where would I find a Ceriodaphnia culture?  Are they commercially available or do I need to grub around in some mucky ponds and get covered with mosquito bites?  Cuz I’m a mosquito magnet and my knees are well past the hiking stage.  😝 

The only place I know that sold them commercially, the owners retired last year and shut the business down. If you live near a university with a toxicology department they might have some. Otherwise if you really want some I could send for cost of shipping.

[OnlyGenusCaps]

On 5/4/2022 at 7:09 PM, modified lung said:

Well all that's about to change because daddy bought a microscope ... that's me …. I'm daddy.

What an amazing thread!  Thanks for putting all of this up here...  Daddy? 🤨

[modified lung]

On 6/2/2022 at 5:21 PM, OnlyGenusCaps said:

What an amazing thread!  Thanks for putting all of this up here...  Daddy? 🤨

I actually prefer "father" and in a British accent.

[OnlyGenusCaps]

On 6/2/2022 at 8:29 PM, modified lung said:

On 6/2/2022 at 7:21 PM, OnlyGenusCaps said:

 

I actually prefer "father" and in a British accent.

Can we go with "pater" and be all Latin about it?!

[Anjum]

This is all so interesting! Yes, how do I do this? I just became interested in culturing my own live foods. I have a pond & a creek in my back yard. The pond is only seasonal, it dries up in the dry part of the summer (which is only 2 months). But it's teeming with life right now. All kinds of water bugs & tons of tadpoles. 1st batch is just sprouting legs & now there's a 2nd batch coming on. I've wondered about just scooping up some water & substrate, putting it in a tank & observing. The only reason I hesitate is because idk if I can introduce something harmful to my tank? I know I've seen planaria in substrate from the creek. 

[modified lung]

@Anjum planaria and snail leeches are the two pests I find the most often when collecting. If you try to avoid collecting any substrate or plant matter, just fill a jar with water, then it's usually not an problem.

If you have to collect substrate or plant matter then after an hour or so transfer everything you collected from one container to another. A lot of the planaria and leeches will still be attached to the side of the container you just poured off. One time never gets them all so you'll have to transfer containers every day until you don't find anymore pests for a few days.

Another way is letting the oxygen get really low in your collection jar. The planaria and snails seem to be the first to come up to the surface. But this is a lot more risky.

[Anjum]

@modified lung great, thank you! I think I'll try it with a gallon jar to start so I don't introduce anything into my tanks. Maybe I'll do 1 w/ pond water & 1 w/ creek water, see if they're different. I might have to try that cell phone microscope thing...

[Torrey]

On 6/9/2022 at 4:33 PM, Anjum said:

@modified lung great, thank you! I think I'll try it with a gallon jar to start so I don't introduce anything into my tanks. Maybe I'll do 1 w/ pond water & 1 w/ creek water, see if they're different. I might have to try that cell phone microscope thing...

This one has worked decently for me, took a little playing around to get good images.

 

Once I got the hang of it, I could identify tiny bugs on a tiny duckweed leaf:

Next trick is consistently getting it to focus. I learned the key is to use the pro setting on the phone, and play with ISO until you get the distinction you need. Then, you can put your fingers on the screen to magnify. Which helped me identify that one of my endlers had eaten a dog hair, and didn't have intestinal parasites. I could see the dog hair, but due to water movement in the tank it looked like it was moving. It wasn't.

My stress was alleviated.

 

[Anjum]

@Torrey oh the dog hair I'll see... 😅

Thanks for the scope rec! It's only $10! 

[nabokovfan87]

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.