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Re: Daphnia and their differing requirements (aeration)

Hi John,

I know this is slightly off topic from the original posts but I too have
noticed the way a lot of publications recommend no aeration for "Daphnia".
I actually posted on this list a few months back about D. magna and
whether it was a good idea to aerate them or not (I was new to magna,
having only reared pulex). I therefore did a lot of experimentation and
found a lot of differences between magna and pulex in terms of
requirements. Pulex doesn't seem to like vigorous aeration (or any
aeration at all I've found) but it is very resistant to a variety of water
conditions and cold temperatures. I don't keep my magna cultures
outside (only my pulex) so I don't know how low their low-end
temperature tolerance is, I have found that magna do very well with good
aeration and they seem not to mind how vigorous it is. However they do
seem to be far more sensitive to water conditions than pulex and I find I
have to change at least half of my water at least every two weeks to be on
the safe side whereas my pulex can go for a lot longer without any ill
effects (I don't feed "dead foods" - only algae/euglena, so fouling the
water takes a while and results only from waste metabolite build-up). 
I also know that within species, all the different strains can have
varying physical traits which can be quite frustrating when you try and
keep them and/or identify them.


> Date: Thu, 15 Oct 1998 20:36:06 -0400
> From: "John M. Burns" <jmburns at pressroom_com>
> Subject: daphnia myths
> As I've suggested in several messages to this and other lists and to
> individuals, no two situations are the same.  I use a bubble wand in my
> tanks; one of the referenced sites suggests air bubbles kill.  I think the
> current (and lots of light) are very helpful.  I've also recommended water
> changes.  I've sugested people split their starter culures up and try
> different things.  I think there's so much difference in water, etc and
> maybe in "strains" of daphnia that you really have to experiement to find
> what's right in your own situation.  I know I killed off several starter
> cultures before I found what works for me.  And I've yet to get enough
> dapnia pulex to have a good source of food for fish... I get just enough to
> keep the culture going.  Very irritating.  And I killed off my suposedly
> unkillable monia culture.
> Now dahnia magna, on the other hand, is realy appreciated by my rainbow
> darters.  It's worth the effort to raise them (the daphnia and the darters).
> It comes down to this:  If you want the truth, you have to fish through a
> lot of information (yes, that's a pun).  I've never tried to hatch
> ephippia.  I just believed the freeze/thaw stuff and moved on.  Now, should
> the occassion arise, I know to try.


"Language has not the power to speak what love indites:
 The soul lies buried in the ink that writes." 

  eirinn at valhalla_com  (http://www.maths.tcd.ie/~jpc)