10.19.09

Daphnia Question

Posted in Uncategorized at 12:11 am by livefood

Subject: RE: question

Hi Jim

Thanks for the answer. Want to ask you questions on Daphnia culture.

Can a culture stay viable indefinitely for up to 3 mos without anyone to care for on just green water alone.
I go out of the country anywhere from 1 to 3 mos and was thinking of leaving them in my outdoor 55 gallon plastic drums where in the winter it can get to 40 degree F and 90 degree F in the summer. The barrel will get full sun exposure long as the day allows.
Can the culture kills itself by depleting the green water? Or can the culture be self-sustaining from the daphnia explosion then a minor die off from overpopulation resulting in more pollution hence green water and the culture just recycle itself over and over from the daphnia that are still alive???

If the above scenario is not possible what other live food culture do you suggest more appropriate for my situation?

Thanks

Liam

_______________________________________________

Liam,

The scenario you outline “sort of” works. The problem you would run into is that you do no include water changes in the outline. Like all aquatic critters, the nitrite/nitrate levels will catch up with the population sooner than later (in this case later…but will still catch up).

In a natural setting, you scenario is pretty much what happens BUT the water will frequently dry up OR when the nitrate levels get too high the population crashes. The water will either come back or the quality improve through the addition of rain (usually). This accounts for the tremendous Springtime blooms of daphnia following the algae and the mid-summer crashes as the algae and daphnia suffer through the declining water quality.

Also, the daphnia are a livebearing creature when conditions are ideal and switch to an egg laying colony when the conditions decline. The eggs stay viable through the bad conditions and hatch when conditions are once again ideal.

We use a system of barrels for our production. One set of barrels housed a colony of goldfish. We fed the goldfish and they produced excellent greenwater for us.

A second set of barrels (smaller, but the size doesn’t matter too much unless they are too small…ours were 24 gallons) housed the daphnia colonies.

A 50 gallons of greenwater more-or-less supported a 24 gallon culture of daphnia with a minimum amount of boom-bust cycling.

While it was helpful to feed the goldfish every day, we have gone extended periods (6 weeks) without feeding and didn’t loose any fish. We had 16 barrels with 5-6 fish in each and were gone for that 6 week period numerous times…never a problem.

We installed a spigot on the bottom of the daphnia tanks and harvest the daphnia by holding a fish net under the spigot and catching them as the water from their tub flowed out.

We fed the daphnia from the goldfish greenwater by taking a bucket full of greenwater and pouring it into the daphnia tub. We then backfilled the goldfish/greenwater barrels with fresh water (we never bothered to declor that water…never had a problem).

With this system, the daphnia and the goldfish received water changes…the daphnia were fed everyday when we needed a lot of food and less when we didn’t. The system crashed occasionally but it was usually related to something odd occurring…and not related to the methodology of the system.

I would think that if you left a very healthy culture which had been recently fed, you would find some daphnia in the system when you came back after 3 months…the water would need to be changed and they would need to be fed, but the colony should rebound and be harvestable in a few weeks or so.

Where do you live, the temperatures you mention sound just about like ours.

Take care,
Jim
The Bug Farm

thumbnail_bugfarm

Comments are closed.