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Re: Daphnia and Spirulina

 Miles Morrissey <mmorriss at sophia_smith.edu> wrote, Monday, Apr. 21

>I bought some Daphnia from DAELCO a couple of weeks ago to see if it would
>clear up some green water I was culturing in  a newly setup tank at work.
>The directions for culturing Daphnia warned not to use tap water as many
>systems include heavy metals that kill the Daphnia.  This tank had been
>set up for several weeks with some struggling echinodorus and Vallisneria
>as well as some stem plant cuttings that I had added to try to compete
>with the green water;  Therefore I thought the water might be sufficiently
>aged to support the Daphnia.  Anyway, I put them in on a Friday and they
>were all gone on Monday.  Green water;didn't make a dent.  I'm assuming,
>correctly I think, that Otto's (the only fish inhabiting this tank
>currently) do not eat Daphnia.  My question is how do people successfully
>culture Daphia?? Would some survive to reproduce in a heavily planted
>tank.  I used to use Convict Cichlid Fry as live food until I found that a
>couple always find aq way to survive the first couple of weeks and
>eventually turn the tables of the Pearl Gouramis.  Anyone know when the
>live food news group will be back on line.  Any one know where I can get a
>starter culture of Daphnia for less than the $11 you end up paying DAELCO
>to send you some???
I bet the Ottos ate the Daphnia.  I have not had experience with Ottos and
Daphnia, but I have seen a single Corydoras catfish clean out every single
Daphnia in a 29 gallon tank in 24 hours.  Most popular aquarium fish can
quickly get every last Daphnia.

You can get various species of Daphnia in any small pond, but care has to
be taken to separate them from other invertebrate nasties and unwanted hair
algae. This can be done with small dishes, a magnifying glass and an
eyedropper. Only a few individuals have to be separated, because they
multiply rapidly if given green water.   The species that swim in open
water will come up near the surface in the evening after sunset and can be
netted.  There is another very common species that does not swim in open
water, but hangs by its antennae on plants or debris in shallow water.  It
can swim if disturbed, but generally is motionless.  Filling a quart jar in
a shallow, weedy area usually pulls in 5 or 10 of these.  I recommend
culturing Daphnia in a gallon jar or small aquarium by feeding them
portions of green water.  Keep some ramshorn or pond snails in with them,
and transfer some of the Daphnia to any aquarium you want to clear up after
you have removed all the fish.  After they have cleared up the green water,
I would not return the fish immediately, but would try to encourage the
plants to grow for a few months until they are well established and
numerous. With thicker plant growth, green water is not as likely to
return.   Keep several cultures of Daphnia in jars or tanks without any
fish so that you will always have them available.

RE Spirulina

Spirulina is a bluegreen alga (Cyanobacteria).  See The Toxins of
Cyanobacteria, Scientific American, Jan., 1994, p. 78.  The author (Wayne
Carmichael) says that Spirulina is not toxic, itself, but he worries that
Spirulina collected for human consumption may be contanimated by other very
toxic species of Cyanobacteria.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174