Daphnia?

I have tiny white specs swimming around my tank. They are visible
with the naked eye, but with a 30x loupe look like round blobs with a
little bit sticking out. I am guessing they are daphnia, but does
anyone have any other ideas?

Daphnia are okay with me as they feed fish and eat single-celled
algae, but I am concerned they might be something else.

On May 10, 9:04 am, g_i_n_k_o <g_i_n_....DeleteThis@visi.com> wrote:
> Vreejack <vreej....DeleteThis@yahoo.com> wrote:
>
> : I have tiny white specs swimming around my tank. They are visible
> : with the naked eye, but with a 30x loupe look like round blobs with a
> : little bit sticking out. I am guessing they are daphnia, but does
> : anyone have any other ideas?
> :
> : Daphnia are okay with me as they feed fish and eat single-celled
> : algae, but I am concerned they might be something else.
> :
>
> From the description, these are ostracods. There is a UK Microscopy
> site with a good overview on them. Google for details.
>
> Daphnia -vs- Ostracods
> daphnia swim in jerky motions, ostracods swim in a smooth manner.
> daphnia frequently have an orange or brown color, ostracods are white or green
> daphnia at maturity can be 10 times larger than ostracods at maturity

This sounds right. The description of the movement is dead on, and
as they all seem to have the same tiny size I assume that is the tiny
adult stage, which is barely visible when lit from behind. Alas, they
are probably too tiny to feed the fish, but they do not seem to be
present in any great number, either. They were probably present in
the soil I dug up, which formed part of the bank of an intermittent
stream which is eroding its way down to the water table.