I have just noticed that in one of my small tanks, there are what appear to be 'worms' stuck to the glass that quickly slither all over the place (on the glass). What are they? Are they things that should be (somehow!) removed?
Are they very small and white? Could well be bacteria from a filter. I sometimes see them in my tanks. The fish often eat them up eventually and they are nothing to worry about.
Hugs,
P.
Edit:Thought I'd add you can sometimes get these growing to a seeable size due to overfeeding your fish. hence them getting the waste, so to speak. So it may be worth cutting down the amount you feed a little.
Are they white/transparent? Sound like planeria, totally harmless, normally get eaten by fish but if you feed your fish too much they can thrive in a tank- just cut back on feeding a tad or increase in tank maintanence(as it could just be too many general nutrients in the tank) and they should go .
I agree with Tokis-Phoenix; they are probably planaria. They are not harmful in themselves, but they usually appear when you are overfeeding your fish, and that could be a problem.
Since other, more harmful bacteria also feed on uneaten food, be sure to cut back on your feeding. If you are worried about the fish getting enough to eat, try giving them two small feedings instead of one big one.