what is the white worm looking things that attach them selfs to the glass of a fish tank?? is it bacteria?

Answer 1

These could be planaria (http://www.caudata.org/cc/images/articles/critters/planaria1JOHNSON.jpg ) if they are attached to the glass and move like a snail. If you have a lot of these, you probably have too much gunk in your gravel or are overfeeding your fish. When you do a water change, clean down into part of your gravel with a siphon to get out all the fish waste and do a different part of the tank each time you clean. Only feed your fish as much as they'll eat in 2-3 minutes twice a day. With less to eat, they'll starve themselves out.

There are also small flies that lay their eggs in the water. These hatch out into something that looks like a small worm, but they swim. These won't hurt your fish (and some fish will eat them). Eventually, they'll turn into flies and leave.

Answer 2

The tiny quarter-inch, thread-like worms you see are just part of the aquarium ecosystem, like worms in your yard. Nothing to worry about. Keep your tank filtered, but don't worry about these. If you look closely, you will not only see them on the glass, but on your fish, and floating all over the tank. nothing to worry about. Every tank has these.