Daphnia Culture "Help"

[jwcarlson]

I bought two daphnia magna cultures from Carolina just short of a month ago.  I started them in two separate 1/2 gallon deli containers and have been feeding them mostly spirulina powder every few days.  Sometimes I'll mix up spirulina with yeast and/or brown rice flour and feed that.  Everything seemed to be going well and 4-5 days ago I started a 3rd culture by netting out some and putting them into a gallon pickle jar.  All three cultures have air lines with slow aeration, big bubbles, no air stones.  One of them has almost no daphnia left, a few days ago I poured the cultures into clean containers because the ones they were in were growing goop and I couldn't see them.  The decrease in daphnia in this one culture in particular did not coincide with me doing the cleaning.  It seems to have been declining.  I never noticed anything drastically growing in population, but they were increasing for awhile with obvious new young dapnia making up the vast majority of the population.

I've not tested the water, so perhaps there's a lot of ammonia... the bubbles cluster up a lot on top, but I assumed that was due to the general scum in the container.  I've been topping them off with the same water I started the cultures with which were "spring water" from the grocery store.  I've fed a handful (like 20 total) adults to my apistos and they are wild about them.  I'd like to get these to take off, but I'm missing something.  Wondering if I'm not feeding them the right stuff... or not keeping the water clean enough... or maybe a combination of things.

Attached is a little thing I saw darting around in the culture that seems devoid of daphnia now.  I think is this a copepod of some sort?  What I'm wondering is if they could be causing the issue?  I haven't noticed them in the other cultures, but that absolutely doesn't mean they're not there.

[Guppysnail]

This time of year most folks keep their house warm. Mine sat in front of a central air conditioner vent and did great. I noticed when my hubby kicked the heat on that comes out if that same vent my adults perished. 

[Lennie]

I think keeping them in small containers is no help. I have a single plastic container which around 60 liter. Bigger is better

Spirulina can cause ammonia spike quite fast. Usually uneaten sera micron start causing 0.5ppm ammonia reading in a fry container around 30-45 mins or so and it is %51 spirulina. Probably you are having issues with parameters and how small the 1/2g is so it is very hard to control the parameters

I feed mine a mixture of active yeast and spirulina but tiny amount of both. I prepare it fresh for every feeding. I feed my culture once every 2-3 days, and other days they snack around the algae growth around. If you have access to green water that would be great. I tried to culture mine at home with fertilizer and long lighting but didnt work for me

[Guppysnail]

On 1/2/2024 at 1:45 PM, jwcarlson said:

I think is this a copepod of some sort?  What I'm wondering is if they could be causing the issue?

Those are copepods. They cohabitate well with daphnia.  No issues. They do make fabulous Tank inhabitants for fish you are encouraging to spawn. 

[jwcarlson]

I bumped both of the smallest ones into 2.5 gallon containers tonight.  There's copepods in both, not that it matters at all.  There's still some daphnia in the worst one.

I've got them in drink containers so it should be fairly easy to change water.  I'm probably overfeeding them, that seems to be a common theme for me. 😄

@Lennie Out of curiosity, how is your fry container filtered?  

 

[jwcarlson]

On 1/2/2024 at 5:19 PM, Guppysnail said:

This time of year most folks keep their house warm. Mine sat in front of a central air conditioner vent and did great. I noticed when my hubby kicked the heat on that comes out if that same vent my adults perished. 

Our house is set at 58, but the basement is actually a bit warmer.  Probably 60-62.

[memorywrangler]

On 1/2/2024 at 5:38 PM, jwcarlson said:

I've got them in drink containers so it should be fairly easy to change water. 

I did this for a long time for moina (like small daphnia).  The water change easiness is nice, but there were two problems I ran into:

1. After about 18 months the containers develop cracks due to fatigue and started to leak.
2. I couldn't clearly see what was going on in the cultures.

I shifted to 2.5 gallon aquariums, which are only marginally more expensive and allow a much better view.

[jwcarlson]

Thanks, @memorywrangler, it wouldn't surprise me that the seams fail on these!  I have never seen 2.5 gallon aquariums, I'll have to keep an eye out.

[TOtrees]

I keep a 20 gallon daphnia culture, and a backup in a 5 gallon bucket. These larger sizes give great stability, and don't require a lot of water changes. Like shrimps, the culture is most sensitive when new.

Couple tips: add some pond or ramshorn snails to help with cleanup. Basically, digested food (poop) is better to have lying around than undigested food (remember that daphnia are utterly incapable of eating food once it's settled). You'll get a better sense of how much food you're adding from the number of snails than from the number of daphnias. Snail explosion → dial back the food. Snails stable → good to go. Also, keep calcium up by adding a sprinkling of crushed coral on the floor, and toss in the occasional piece of cuttlebone. 

Just to check, when you do water changes are you using aged tank water, or treated tap? I've heard daphnia are not tolerant of dechlorinator. 

My food is around 3 parts spirulina to 1 part each of rice and chick pea flour. In my 20 gallon culture, I change around 5 gallons every 2 weeks. I don't see much/any ammonia, but I think the tank has a strong bb colony despite not having a filter. Eg they're on the glass, in the mulm, on the coral, etc. I vacuum around ever 3 months or so. 

Other thoughts: I think these guys are incredibly resilient to temps, ammonia and low O2 in nature. I wild collect a few every spring, and I watch the vernal ponds they're in diminish and disappear. The number and density of daphnia that persist in the late stages of that process is crazy. When a home culture crashes, I tend to think it's not ammonia or O2 or whatever directly, but rather those factors plus other conditions (light? temp? humidity?) are telling the adults to give up on survival and invest in the dormant egg type, as opposed to the live young. 

[jwcarlson]

@TOtrees what kind amount can you expect to harvest from a culture that big (20 gallons)?

My water also seems to love to grow hair algae which to me seems like a daphnia killer as I assume they'll get tangled up in it.  Has anyone experienced that?  Will daphnia eat off the sides of the container?  I know they're kind of a filter feeder, but I read people talking about them eating algae fairly frequently.

When doing water changes/refilling I use water from a tank now, but initially when I set it up I used bottled water.  Or at least I think I did, but I got paramecium cultures the same day so I might be crossing that up.  I know I used bottled for the paramecium for sure.  It's been tank water since, however, for the daphnia.  

I don't think I have any snails in with them yet, that's easy enough to do.

Is aeration necessary or at lest of benefit?  I have very low bubbling, it's very dialed back.  But in a bigger container I could probably turn it up and still not mix them like brine shrimp eggs, which seemed to be the issue in the smaller containers.

Edited January 3 by jwcarlson

[TOtrees]

Great questions! How much I harvest depends on what method I use, how often I harvest, and how heavily I've been feeding the culture. I usually feed daily, but they can go 2-4 days without easily. From my 20 gallon, I get maybe a heaping tablespoon when I do a "heavy" harvest. That's enough to feed some to all the tanks that need it (~8 of my tanks? with inhabitants ranging from a dozen shellies to 50 small community fish). 

I use two methods to harvest. Easiest (lower yield) is to run a brine shrimp net through the tank. That gets me a few dozen to a few hundred daphnias, about what you'd get in a big starter culture. The (slightly) more involved method is with water changes. I use a 3/4" plastic tube to drain 5 gal from the 20 gal tank, aiming to draw water from the parts that have the heaviest concentration of daphnias. That removes maybe 50-60% of the daphnias in the culture. I pour that removed water through a reusable coffee filter then feed the daphnia to tanks. The equivalent from the 5 gal bucket culture is removing 3 gal, so more like a 60% change. In both cases, I just refill from any nearby tank. Refilling tends to disturb all the mulm and crud on the bottom, but it settles back out and the daph don't seem to mind. 

My airflow is from an open-ended 1/4" airline. Runs maybe 5-10 bubbles per second, enough to create an uplift and move the water around, but not enough to roil the surface. Certainly not the amount of air that bbs hatcher gets. 

If you're water is growing hair algae, dial back the light. I do get some clumps, and remove them periodically. Daphnia do eat algae, but only in the green water sense, and not in the grows like a plant sense. They cannot graze, and will not eat off surfaces. Some keepers try to keep daphnia in green water, and some claim to have succeeded. To make that work i think you'd need a significant amount of fert, at TON of light, and frequent harvesting. I've seen daphnia clear an outdoor pond with green water in just a few days, and that's powered by sunlight. So in an indoor setting, if you're lucky enough to have a green water tank, it's probably under super bright lights, and the daphnia will still clear it out fast. And make more daphnia so the green water can't come back. Unless you're diligently harvesting, keeping the density of grazers (daphnia) way below the growth rate of the algae. I find light doesn't hurt, but i don't rely on it for making enough algae to feed the daphnias. Anything between very low and medium brightness (in aquarium plant terms) is fine.

[Schuyler]

On 1/2/2024 at 3:19 PM, Guppysnail said:

This time of year most folks keep their house warm. Mine sat in front of a central air conditioner vent and did great. I noticed when my hubby kicked the heat on that comes out if that same vent my adults perished. 

I second this. My outdoor culture did amazing in late spring, slowed down during summer, exploded again in fall, and now that it's winter it's just barely dragging along. They seem to like cool but not cold.

Also, bigger containers have been easier for me than small ones.