uhh--there are hundreds of species of planaria
(Turbellaria) in a variety of colors and
sizes. The ones I've seen most frequently are
brown and greater than one inch in length.

-coelacanth

P.S. Sorry to get all defensive, but I raised
these guys for a science fair project one
year long ago and I'm quite fond of the
little buggers.

"Dunter Powries" wrote in message
...
Planaria are white, somewhat smaller than described, and will usually be
seen on the glass after lights-out.

coelacanth wrote in message
. com...
I think these are probably planaria or other flatworm. They live
on excess food and are usually harmless (though they have near
relatives which are parasitic and not usually seen in a free
swimming stage). Try feeding a little less if they get out of hand.
Many fish relish them, so they may just disappear.

They may have come to you on a plant or unnoticed in the
bag with a fish.

-coelacanth

"Jim K" wrote in message
...
I need some help identifying worms in my aquarium. My tank is heavily
planted, and I recently found some worms moving along the substrate.
They
are reddish-brown, about 2 inches in length and 1/8" in diameter. I
would
supply a photo but they disappear very quickly.

My questions a

1. What are they?
2. Where would they have come from?
3. Are they harmful to the fish?

Thanks in advance.