freshwater fish-wormlike squiglies

Question
We have had our twenty gallon tank for over a year now and in the last three months have switched to an under gravel filter.
We mostly have mollies(5)with a few tetras.  The mollies have recently had a few babies, six total.  We do have one live plant, oh, and an algae eater...named Al.

Recently I have noticed little white worm like things swimming/floating through the water and crawling on the side of the tank.

I have treated the tank for parasites and fungus, but that doesn't seem to affect these little squiglies, so now I am wondering what they are and if they are harming my fish. I have noticed my fish eating these off of the side of the tank.

pH remains around a 7.0 and I use an ammonia cartidge with the filter.  I have also treated for nitrates.  Stress zyme was also added to the water several months ago to help clear up cloudiness and prevent an ammonia surge.  

Answer
Hi Bonnie;

These are "Planaria" and are totally harmless to your fish. What isn't harmless is the overfeeding that has caused them to overmultiply. I have gotten them from time to time too. I just cut back on how much food I feed, vacuum the gravel every week for awhile and they fade away. The fish will feed on the planaria more and more too as you lower the addition of food, further decreasing their numbers.

Once you get the crud out of the gravel they simply starve out. There is no medication or chemical that kills them. All it does is stress the fish. They even survived a bleach treatment in a tank I had no fish in once! Yikes!

Followups welcome

At Your Service;
Chris Robbins