Join Date: Jan 2013
Location: Sydney, Australia
If they are really tiny, like a few millimeters long, then I had this in my tank not too long ago, if i am not mistaken, these are just the microworms that are naturally occurring in planted tank's substrates. I had otos in my tank when this happened but they were fine, did some research on them, apparently they only appear due to a lack of oxygen in the tank and go to the surface. They are not harmful, should go away after a while, mine disappeared after a few days.