tiny daphnia

I have been maintaining a few cultures of ostracods for a while and have recently found a stranger in the tanks, a tiny daphnia that is smaller than any I have ever seen before. This is good news for me, as I love finding potential new live foods for my fish. I haven't the slightest clue as to what species it is or where it came from, but I managed to isolate what I thought were six juvenile individuals. That was last night. I put them into a 10ml container, floated them in the small tank they came from, fed them live concentrated algae, and added strong lighting. It turns out that the six were actually adults, as they have already produced about 20 super small juveniles. The adults are about the size of a newly hatched brine shrimp. I now have them floating in a 50ml container with more algae added. I am pretty excited about these guys, as they may end up replacing my current favorite live fry food, newly hatched ostracods. I have also seen a few more in my ostracod tank, so if this attempt at isolating them fails, I should be able to try again. Does anyone know of a good reference I can use to determine the species? I would love to know what they are and where they came from.

Hi Auban,


This is a good one:


Pennak's Freshwater Invertebrates of the United States:

Porifera to Crustacea
-- by Douglas Grant Smith

What kind of ostracods do you raise?

Cheers,
Dona

thanks for the reference, ill have to look into it. i have no idea what species of ostracod i keep either, some type of vernal pool variety, im guessing since it wont reproduce in the presence of fish. well, i keep two types, one is smaller and will reproduce in tanks with all but the smallest of fish, the other gets a tad larger than a daphnia magna and lays lots of eggs that must be dried in order to hatch, though i can usualy get some to hatch out with a water change. whever i move somewhere, i begin looking for native critters i can raise as live food. out of the hundreds of things i have cultured in the past, the only live foods i have ever actualy purchased could be counted with one hand(brine shrimp, fairy shrimp, canadian nightcrawlers, and dubias roaches). i would say that i am much better at culturing zooplankton than i am at raising fish. the new mystery daphnia may have come in with the faiyshrimp eggs i ordered a couple years ago, but i have never seen them until now.

Some other tiny Daphnia-like cladocerans they might be are Ceriodaphnia, Moina, Bosmina, Chydoras, etc.

Auban--You should write a how-to manual on your zooplankton culturing methods--I’d gladly buy a copy!

update: their numbers have grown again, so i am preparing a half gallon tank to recieve them. i am innoculating it with green water. the green water is actually quite easy to make, just get "phyto feast", a concentrated liquid solution of 5 different kinds of marine algae. i found by chance that if you feed anything in fresh water with the stuff, it developes a very healthy culture of green water. it sometimes becomes annoying when my tanks start turning a little green... i also added a little bit of my fairy shrimp blend. it is a blend of various foods that i have found to support very rapid growth without fouling the water.

i have found that fairy shrimp, ostracods, and daphnia grow quite well on it and it works esspecialy well for me since it lives until it is eaten. that said, fairy shrimp will grow just about as fast as you can feed them as long as the water quality doesnt degrade. i can add enough phyto feast to reduce visibility to about an inch and the fairy shrimp still manage to make the water crystal clear within two days. im hoping this new water flea thing can do the same.

disaster almost struck...

while i was at work thursday, my daughter managed to get ahold of the 50ml cup that i had the culture in. she poured the water into a small container that had fish tank water in it... not good. the presence of fish can stop them from reproducing. fortunately for me, i had already set up the tank they were to be transfered into. in they went. even though they were transfered a day early they didnt die, and it seems that the water from the fish tank did not stop them from reproducing. i counted about 50 or so that i could see, which means there are a lot more than that since i can only see abut an inch into the tank because of the algae.

right now it is just a matter of time before i step them up to a 20 gallon bin i have set outside. they will be transfered once they start to overpopulate the container they are in.

as an aquarist, these are my favorite kinds of projects. i enjoy isolating cultures of little water critters even more than i enjoy breeding fish.

that said, i do love a successful spawning...

Auban--You should write a how-to manual on your zooplankton culturing methods

i enjoy isolating cultures of little water critters even more than i enjoy breeding fish.

I would read that manual.

All of my aquatic mini-life culture in the past have gone terribly wrong. My friend and I used to chuckle over the irony of how she could keep her sea monkeys alive for years and years in a tiny bowl and I, the fish breeder, couldn't keep them alive for a month. It's gotten to the point where the only thing I keep is non-aquatic worm cultures, since I can't possibly mess up the water and kill those. I'm supposed to be starting breeding marine rotifers soon for a project and all I feel is ominous wariness, not excitement. So, yeah, I would read that how-to guide. Could you write an article on your native crustacean cultures for American Currents?

Edited by EricaWieser, 10 June 2012 - 12:29 PM.

hmm... well, i have another 24 hour duty tomorrow, so ill start writing out my methods. i think most people would be surprized at how i do it. my methods at times can be very crude.

take my latest project for instance. i managed to follow a stream that dries up every year untill i found a tiny pool of water, about half a gallon. i collected about two cups of nasty water from it as well as some of the mud. i found three different types of ostracods and several of a completely white scud. right now i have them in a cooler outside and will leave them there for the next several weeks. no feedings, no care, just left in the sun.

by the time it gets close to drying up, i should have more than enough to isolate some cultures from it.

Some other tiny Daphnia-like cladocerans they might be are Ceriodaphnia, Moina, Bosmina, Chydoras, etc.

thank you!
this gave me the lead i needed. it turns out that i have some species of Ceriodaphnia.

well, my culture failed. i guess they werent ready to go into the next container, they all started laying eggs. oh well, at least i still have the origional culture they came from, so i should be able to isolate them and try again.

in other news, today i aquired a very healthy culture of daphnia pulex from my local waste water treatment plant. if i had the right kind of net on me, i could have collected several pounds of them in just a few minutes. as it was, the guy there who collected them was able to simply scoop enough into a cup to fully populate a ten gallon aquarium. i am going to be developing a feed for them. they seem to love the mix i have for my fairy shrimp, but they eat a LOT more than my fairy shrimp do, so i need something a little more economic.

So you leave the cooler in the sun? How high does the water temp get? Does it matter? Thanks.

considering where you got them, i have some ideas for a free and readily available food source.

in other news, today i aquired a very healthy culture of daphnia pulex from my local waste water treatment plant. ... they seem to love the mix i have for my fairy shrimp, but they eat a LOT more than my fairy shrimp do, so i need something a little more economic.

So you leave the cooler in the sun? How high does the water temp get? Does it matter? Thanks.

yes, i leave it in the sun, usually nearby something that will give it at least a little shade for part of the day. the temp gets to about 90 degrees. if it starts to get too hot everything stays at the bottom. if i see that i move it a little more in the shade. other than that, i dont do much.

daphnia reproduce better when they stay under 80 degrees, but they dont seem to mind a fluctuation too much, as long as it doesnt stay that hot. the fairy shrimp i raise dont seem to care, and my ostracods actually do better at around 90 degrees.

Edited by Auban, 13 June 2012 - 04:01 PM.

considering where you got them, i have some ideas for a free and readily available food source.

...
...
i guess i could just poo in the tank...

that would make for an interesting explanation to my first sergeant when i request a barracks room to sleep in....

seriously though, i want to try using wolffia as feed for them. it is one of the few things that a hobbiest could grow inside their house in large enough quantities to feed daphnia(or anything). at around 20% protein and 44% carbohydrates, it should be a good feed. combine that with the fact that it can pull dissolved organic carbon out of the water, grow without light, and double its mass every two days, it should be an excellent feed.

Edited by Auban, 13 June 2012 - 04:27 PM.

It's been hellishly hot here in New Mexico, and all of my D. magna and D. pulex cultures in the greenhouse have failed. I've been trying to culture some of the smaller cladocerans and ostracods that have come in with fairy shrimp eggs to varying success. I think that I have some Ceriodaphnia and have also been working with these. Some random observations:

They seem to have a limited temperature range that they will tolerate, and I agree that whatever species (might be several species - when I get a couple of hours free I plan to key them out with Pennak) I have seem to do best at about 80 - 85 degrees. Any higher and they crash, any lower, ditto. Tried to bring some inside as assurance colonies, all died under artificial light.

The ostracods that I have (several species) in culture like it even warmer, about 90 degrees and they're reproducing like crazy. However, they respond poorly to the addition of any new water in the bins/tanks and they're populations get dinged with any addition of new water - old fish tank water, OR water, etc, - I've tried a number of variations. I'm wondering if these are boom and bust desert species that seem to need the changes in water quality that come with evaporation at high temperatures.

And a question:
I have found several references to using old fishtank water to culture daphnia. When I use it, the colonies stop breeding and/or crash. For some reason there's still a lot of misinformation floating around about raising cladocerans despite them being some of the most commonly cultured species on the planet... Have any compounds in particular been identified that are present in the water that trigger the response to not reproduce? Has the presence of fish been demonstrated to have this effect across the board or just with a few species?

It's been hellishly hot here in New Mexico, and all of my D. magna and D. pulex cultures in the greenhouse have failed. I've been trying to culture some of the smaller cladocerans and ostracods that have come in with fairy shrimp eggs to varying success. I think that I have some Ceriodaphnia and have also been working with these. Some random observations:

They seem to have a limited temperature range that they will tolerate, and I agree that whatever species (might be several species - when I get a couple of hours free I plan to key them out with Pennak) I have seem to do best at about 80 - 85 degrees. Any higher and they crash, any lower, ditto. Tried to bring some inside as assurance colonies, all died under artificial light.

The ostracods that I have (several species) in culture like it even warmer, about 90 degrees and they're reproducing like crazy. However, they respond poorly to the addition of any new water in the bins/tanks and they're populations get dinged with any addition of new water - old fish tank water, OR water, etc, - I've tried a number of variations. I'm wondering if these are boom and bust desert species that seem to need the changes in water quality that come with evaporation at high temperatures.

And a question:
I have found several references to using old fishtank water to culture daphnia. When I use it, the colonies stop breeding and/or crash. For some reason there's still a lot of misinformation floating around about raising cladocerans despite them being some of the most commonly cultured species on the planet... Have any compounds in particular been identified that are present in the water that trigger the response to not reproduce? Has the presence of fish been demonstrated to have this effect across the board or just with a few species?

if your ostracod cultures came in with fairy shrimp, they are most likely a desert species. a healthy culture will lay a LOT of eggs, with a small fraction of them hatching without the need for drying. if you empty your cultures you will probably see orange spots all over the detritous, walls, substrate, etc. these are clusters of eggs. i just harvested a three week old culture that had sand at the bottom of it, and got about a third of a pound of ostracods in it. it was enough to completely cloud a planted 65 gallon blue fin killifish tank. i shouldnt have to feed them for a few weeks.
i will let the sand dry and then add water back to the culture, which is nothing more than a large plastic bin i got from walmart. every time i re-hydrate my cultures, i end up with more ostracods than i had before, so much so that i have to continuously feed them to keep them going.

i dont know what species you have, but mine seem to grow best on spirulina powder. i ordered a kilogram on ebay for about 20 dollars and as far as i can tell it will last for a very long time.
as far as water changes go, i dont use water from my fishtanks to top off my ostracod cultures. i use dechlorinated tap water, which always seems to set the culture back a bit, but its not that bad for me since i practice full harvests. my cultures "fail" as a form of regular maintanance anyway.

for the past few days, the temps here have been about 104 during the day, and the ostracod cultures have managed to survive that, sitting out in full sun. defenitely a desert species...

so far as water changes go with daphnia, i have read studies indicating that daphnia only respond to predators that they have existed with at some point in their history. mine dont respond to fish tank water, but i have some in the past that did, so i think its kinda hit or miss on that one.

well, i managed to start another culture of really small daphnia. im not really sure what they are, but they are breeding quickly. their small size leads me to believe that they are either bosmina or moina, but i havent put them under the microscope yet to find out. when i started this culture four days ago, i counted four adults.

here is a video of them.
http://s1242.photobu...0718_191357.mp4

in the video i tell my daughter that they are daphnia. i know that probably isnt true, but i dont think i could explain the difference between a daphnia and a moina to a three year old...

im just glad she is interested in the hobby

when i started this culture four days ago, i counted four adults.

Four days ago there were four adults and now there are this many? wow. Are you feeding them dried spirulina, blendered dandelions, something else?

just green water from the outdoor culture. there was probably more that were small or hiding in the detritous at the bottom, but they have been steadily increasing in numbers. ill post vid in a day or so for a comparison.