This is a discussion on Does my betta have fin rot? within the Tropical Fish Diseases forums, part of the Freshwater Fish and Aquariums category; -->
i did a water change and it seems to be going away but his fins look shorter:(...
Are they like small white oblong shaped things? If they are worm-like, then they are most likely Planaris. In which case I believe they are harmless and are typically a sign of overfeeding as they eat excess food... I can't find anything else that seems to fit your description.... If you could get a picture that could be helpful. However, it sounds like most creatures it could be are usually harmless.
they are way to small for a picture but thats what they sound like. i have removed the pleco and so i can treat the betta but will that also kill the stuff on the glass or will a simple waterchange and regulated feeding help that?
It might. It sounds like you can't really get rid of them, but people claim that plenty of water changes and reducing the amount of food being fed have severely decreased the numbers present. So it's worth a try :)