asta wrote:

Definitely not snails... they swim around through the water
quite fast and have a bilaterally symmetrical body.
Can anyone put a name to these? I always thought that
they were "copepods", but when I search on this
term, I see only salties referred, also mine have a compact
form, no appendages in sight. They are white in colour.

They may well be copepods, even so. The sal****er varieties get a lot
more web sites (marine researchers are weird folk, eh?), but there are
freshwater varieties as well.

There almost no direct action you can take to get rid of them. You
don't want to dump chemicals in on healthy fish, and a full tank
breakdown is a nightmare.

I had a really bad infestation of these in a water-pot. I don't know
what the real name of the setup woudl be - it's a lidded one-gallon
container with a few inches of potting soil, a layer of gravel, and the
rest water. In it is growing, slowly, a Jade Sword. The water at one
point was just loaded with little critters that I assume are copepods.
I put a couple of ghost shrimp in there for awhile, and they seemed to
reduce the population of the bugs quite a lot.

And even if that doesn't work, ghost shrimp are pretty cool critters
themselves


--
Eric Schreiber
www.ericschreiber.com