Feeding Daphnia

[jesper]

I'd like to know what you feed your Daphnia how often and how much? I am trying optimize my culturing methods a bit.

I usually just feed my culture(10l of water) twice a week or so. I keep the culture at 18-20C. I feed with activated yeast. I only feed a couple of grams each time - will check more exactly how much(I am a chemist not a chef ok?

)

Any suggestions of improvements would be appreciated(Yes I have read JC's Daphnia article...).

 

[jennifer]

Like you, my methods are not very scientific. I feed daphnia whenever their water goes completely clear, which is usually every 2-5 days. I feed enough to make the water visibly cloudy, just going by eye (impossible to explain). I feed them by pouring in a mixture of yeast, soy powder and spirulina powder suspended in water.

 

[joeri]

I've red of a method in which you use a tank covered with (floating) algae and add snails.
Daphnia is supposed to feed on the snails expels and other detritus (organic waste) as well as phytoplankton found in the algae.

I haven't tried it myself, but I am about to. I'll let you know how it turns out.

 

[jennifer]

My daphnia tanks have floating duckweed and loads of snails. There has to be some "input" of food to keep the system reproducing. Perhaps feeding the snails instead of directly feeding the daphnia might work, but I think the reproduction would be slower.

 

[jesper]

Yes I have too much snails in my Daphnia culture, I'm afraid that they use up all the Calcium to make their shells. Also, I think the snails might compete with Daphnia for the yeast I feed them - when the snail population explode the Daphnia population seem to decrease.

 

[joeri]

<blockquote><hr size=0><!-quote-!><font size=1>Jennifer Macke wrote on Sunday, 23 January, 2005 - 16:41 :</font>

"Perhaps feeding the snails instead of directly feeding the daphnia might work"<!-/quote-!><hr size=0></blockquote>

Sorry, forgot to add that part.
In the method I discribed above you feed the snails fishfood.

And you have to change tanks every 10 weeks.

 

[killian]

I have set up several daphnia cultures, I bought some yeast powder and mixed up a soloution, is this ok just added until the water goes cloudy?

 

[jennifer]

Killian, yes, exactly. Be sure to use just a little, and let the water become completely clear again before you feed again. After a while, you'll be able to gauge the amount you need to add to last them a day or two, but in the beginning be very careful not to overfeed. You can keep the yeast/water suspension in the refrigerator for 2-3 days.

 

[killian]

would it be safe to add some yeast to a pond to encourage the population to flourish? it is 12'x 12' and about 2' deep.

 

[jennifer]

Good question. I'd be reluctant to put yeast into a pond. I think it's better to let the pond develop its own micro-flora and fauna. If it gets sun, algae will feed the daphnia. Is it a brand new pond? If so, then maybe you do need to feed the daphnia a bit; I'm not sure.

 

[killian]

Hi Jennifer, the pond is not new but I used to keep ducks in it before so i gave it a good clean out and refilled it. I started a few cultures inside and allowed the outside water to mature then released a few hundred daphnia into it.

My question now is, my daphnia tanks have started to develop a good algea growth, should I continue to feed the daphnia or just allow them to eat what grows in the tanks?

 

[jennifer]

Killian - I would say it depends on the kind of algae. Daphnia can only eat the "pea soup" kind of algae that grows suspended in the water. I think in an indoor culture you will always have to add some kind of food for the daphnia - either algae-water or other food.

 

[pollywog]

I use Spirulina powder to culture Daphnia, works a treat, it is also ok to use in a pond.

 

[thomas]

Jesper, if you want to get your daphnia culture growing very fast i suggest you try a high pressure lamp used for green houses. I started use one (gavita 400w)on my culture(witch was very small about 10 adults of D.pulex and 10 0f D.magnum) some weeks ago, and now i have them by the thousands!! The daphnia with this lighting also seem to be much more active-they swim super-fast in all directions, in big contrast to the slow daphnia in the tank with the flourocent lighting. I use the light on 18 hours a day on an 20 gallon tank(and several others smaller ones incase it crashes) with some plants floating, and despite what i read every were, i have found that no circulation works best with this method at least for me, also i do not use stable temperatures it gets warm when the lights on(just above 20C) and closer to 15C when its off, i dont know if this makes any diffrence(gjess i will know when summer comes and heats up my basement) , in fact the only thing i do to feed them is change 50% of their water with week old water(from same container) that has been close to this light. You only need to cull them.

 

[sarah]

I started a culture a few days ago and am using boiled lettuce leaves to feed the daphnia. The waters gone really cloudy, so Im not sure if its worked or not.

 

[louis]

whenever i use spirulina powder to feed them the water always fouls overnight and begins to smell. most of the daphnia die within a day, perhaps i am feeding too much but it seems like the necessary amount in order for the water to look slightly green. i have two small cultures going at the moment which i have been feeding on dried yeast mixed into water and then two small spoonfulls of this is put in with the daphnia every two days, i remember when i once got a triops kit the water in their bucket went completely green with single celled algae in a week or two which is perfect for daphnia to eat, i think its a combination of the pre made triop food and the sort of tea bag thing you put in their water. im going to go get another triop kit tonight and see if i can make a tank of green water for the daphnia cultures.

 

[jennifer]

Louis, how do you add the powder, and how do you decide how much to use? There appear to be 2 different "kinds" of spirulina powder, I've found. One kind makes a nice pea-soup suspension when you mix it with water, but the other kind gets sort of slimy when you mix it with water. The latter type doesn't work too well.

When I use yeast and/or spirulina, I first shake them in a jar of water until well-dissolved, let the heaviest material settle for about 1 minute, then add just enough of the suspended material to the culture to make it very slightly cloudy.

Sarah, it sounds like they were overfed, which is very easy to do when just getting a culture started. Have you gotten them going since you posted?

 

[louis]

i just bought some spirulina powder from a health food shop and mixed it into their cultures, i wouldnt say it goes slimy, i think i have just been adding far too much. i want to try live greenwater because i figure that if the algae is alive it isnt going to begin to decompose and foul the water before the daphnia can eat it.

 

[jennifer]

You should definitely pre-mix any powder with water before putting it into the daphnia culture. If not, then some of it stays in "chunks" and decays rather than being eaten. But if you can manage to keep a culture of green water, that's better and certainly eliminates any overfeeding problem. Personally, I draw the line at culturing food to feed another culture

 

[joeri]

Just to make sure there is no translation issue, when you mention yeast. Is it the same yeast you buy at any store and you need it to make bread?

If so I'm gonna try it.