Twin 5-gallon daphnia cultures

[memorywrangler]

I had to shut down all by three gallon tank at the end of March due to some extended travel, which included my 2x2.5 gallon daphnia/moina cultures.  I left the three gallon tank with a friend.

When I got back home 2 weeks ago, the first thing restarted was those cultures (but upgraded to 5 gallons each). I'm a little obsessed with live food (https://shorturl.at/6Bi6p).

I picked up a back of daphnia from the local fish club auction and split it between the two.  I also added some mulm and algae scrapings from the three gallon and started feeding them my Live Food Food (see link above)

They've been going for 4 days and already are behaving differently.  The left culture had a huge die off and an ammonia spike.  All the large daphia are gone, but they babies are still there.  The right one is doing fine.

If they go well, I'll soon have the problem of what to do with them, because I currently have no fish: 

[Guppysnail]

On 7/19/2024 at 2:25 AM, memorywrangler said:

If they go well, I'll soon have the problem of what to do with them, because I currently have no fish: 

Not during critically hot months because they do not ship well in extreme heat but selling them on eBay is an option. I buy daphnia magna and ostracods as live food on eBay quite a bit. They both go for a nice penny. 

[memorywrangler]

They sure do.  Bags of daphnia are regularly the most expensive thing sold at our local auctions.

I left some mollies that I had with another friend.  Once my newly setup tanks are reasonably stable, I’ll probably pick them up and feed the daphnia to them.

[memorywrangler]

Surprisingly, things have been kind of interesting in the cultures:

• There's a marked difference in color between the two.  I guess the left one has more algae growing.
• Blood worms and mosquito larva has shown up, and the blood worms have formed this cigar-shaped tubes out of the mulm.

The guy I bought the daphnia from keeps his cultures outside in 50 gallon barrels, so the eggs must have hitched a ride.

I think I'm going to have remove them, since I don't want mosquitos or adult blood worms flying around my house.

I also added some Salvinia minima  to soak up nitrates.  The daphnia are doing fine on both sides.

[memorywrangler]

Things are going well in these two cultures:

1. I took some of the green stuff from the left culture and added it to the right, so they look more similar than they did.
2. All the blood worms and mosquito larva hatched, which cause a brief but annoying insect problem in my office.  I hope they didn't lay more eggs.
3. I set up a coop auto feeder on each of the cultures to dispense about 1 pinch of the live food food per day.

These cultures are serving three purposes:

1. Future food source for fish I don't yet have
2. Source for algae and tiny critters to help kick start the establishment of my two other tanks.
3. Testing ground for a complicated daphnia autofeeder system.

For #3, the idea is to use a very stable daphnia culture (e.g., fed by a coop autofeeder) and periodically use a pump to extract daphnia and feed them to a tank.  This might make it much easier to keep things like pipefish, which require constant supplies of live food.

 

[HelplessNewbie]

Í only have very small cultures in jars with a tiny bit of hornwort and bladder snails. I envy your setup and look forward to the autofeeder updates.

[TOtrees]

On 7/21/2024 at 11:15 PM, memorywrangler said:

I also added some Salvinia minima  to soak up nitrates.

 

I keep a 20 gallon and a backup 5 gallon culture of daphnia in my fish room, have been running them for a few years now. I've heard that live plants, while not directly bad for the daphnia, are not recommended bc they'll take nutrients faster than than the "pelagic" green water algae that daphnia largely subsist on in nature. So I don't keep any plants in my cultures, and I clear our clumps of filamentous algae in the smaller one when clumps get to be grape sized or larger.

I've also found that any daphnia culture that is producing enough daphnia to occasionally harvest and feed any reasonable amount to fish, simply can't sustain green water because of... you guessed it, the daphnia clearing it out so effectively. They'll appreciate (thrive on) green water if you add it from a separate green water culture, and they'll go bananas if you add a small number of daphnia to an active green water culture, but you can't keep medium or large densities of daphnia in green water. At least not in my experience. I'd bet that if you blasted really high light levels (approximating full sun) and harvested frequently and heavily it could work (ie keep the daphnia population WAY below the nominal carrying capacity of your setup). All this is to say yes there could be a slight greenish tint to the water in your cultures, but I suspect it's reflected light from the algae on the glass. 

Following to see where the autofeed system goes, I like that idea! 🙂

I've seen your live food thread @memorywrangler, and you clearly have a lot of exp here so I don't think any of the above will be info you don't already know. Mainly adding for others I suspect. Question about something in that thread... you close the section on moina by saying it always crashes after 6 weeks. Is that the moina, or the green water? One thing you might try is a bigger daphnia culture, if you have the tank and/or shelf space. My 20 gallon culture seems to be more stable than my 5-gallon bucket culture. Both only have cheap LED lights more for me than for the cultures. Also, have you checked the appearance of the adults over time, esp after the 1 month time? Clearly from your descriptions you're getting some babies, but I wonder if your adults are switching to producing dormant eggs over "live birth" eggs, and that's why you're seeing the crash? With your microscope, you might be able to see the difference, like this:

[source: https://www.researchgate.net/figure/Daphnia-magna-a-normal-eggs-b-Dormant-eggs-ephippia_fig5_335430917]. 

[memorywrangler]

On 7/29/2024 at 4:50 AM, TOtrees said:

you close the section on moina by saying it always crashes after 6 weeks. Is that the moina, or the green water?

This was the moina culture.  Since I wrote that I had 2 2.5 gallon moina/daphnia cultures set that ran just fine.  The set up was basically identical to the 2x5 gallon setup I described here. 

When I have had green water, the daphnia have really enjoyed it, but I haven't been able to keep it going successfully inside.  My daphnia seem to do fine on powdered food and the guy I got them from feeds his yeast (and they are outside, so I'm sure they get all kinds of stuff).  I also have to believe that they also eat the infusoria that grows in the tanks too, and I've heard they can actually graze off of surfaces.  I'm sure all of this depends on the exact variety.

Inspecting the adults for what kinds of eggs they are carrying is a great idea.

On 7/29/2024 at 3:28 AM, HelplessNewbie said:

forward to the autofeeder updates

I have considered extending my autofeeder idea to include green water.  It'd be quite a system:  a reservoir of green water with a bright light would occasionally dump into a daphnia culture, which would, in turn occasionally discharge into a tank with fish.  Then, all I need to "feed" my tank is light and fertilizer.

[memorywrangler]

The daphnia cultures are doing fine.  The most interesting development is that I tried to start two green water cultures based on the green water I had in my 22 gallon.

On the left, I fertilized with household ammonia (2ppm) and phosphate-rich fertilizer (to 10ppm).  On the right, I used some easy-green.  I'm blasting both with my 120W LED grow light.

It's been 4 days and neither of them is doing much on anything.  I'm tempted to start over, but I added daphnia to the tank with green water, and they cleared it up very well.  Perhaps too well!  I don't have any greenwater starter culture left.

 

. 

 

 

[memorywrangler]

Green water cultures have been hit or miss.  Culture L (on the left) took a very long time to get started, while Culture R (on the right) turned green pretty quickly.  I've noticed a few things:

1. L seemed to get contaminated with something that turned the water yellowish.  I suspect it was either 1) another variety of algae other than chlorella or 2) some protozoan critter that was eating the algae.
2. Both have been very erratic at different times.  R was greening up very nicely and then crashed over the course of a few hours.  The same thing happened to L on some occasions.
3. I cross contaminating the R with some water from L at one point, and it significantly destabilized R.

I'm feeding them with easy green, but not very precisely, which is probably not helping things.  You can really see them green up when I feed, though.

Two days a ago, I completely stripped and sanitized L and re-seeded it with algae from R.  But then I stupidly returned L's air stone to L without cleaning it...\

I also added a high-contrast pattern on the back of the tank to make it easier to gauge greeness (like a secchi disk).  You can see some of changes below.  

[memorywrangler]

The Daphnia cultures are doing great, though.

Whatever variety I have is happy to eat of the sides of the tanks and the sides are wonderfully slimly.

Another forum suggested that eating on the sides was a sign that the culture was about to crash.  I checked for live young (as apposed to resting eggs) and found a mostly live bearing eggs and I see a fair number of small daphnia.  Nevertheless, I turned up the feeding rate by about 6x on the right side culture.  It got muckier and denser pretty quickly, which was interesting.

I've also been feeding the periodically with green water.  Here's the cultures before, immediately after, and one day after removing 2.5 gallons of water and siphoning in almost all of one of my green water cultures.  The left green water went to the left daphnia culture.

You can see how much more algae was in the right green water culture and how quickly the daphnia cleaned it all up.

I'm sure there are many ways to do this and many kinds of daphnia, but I think the absence of snails is really important since it lets the algae grow thick  on the sides.