Okay i've had my betta and it's tank for about a year now.
Well today when i was cleaning the tank up a bit i noticed that there were these white creatures all over the tank walls. I thought that they were just left over food sticking too the walls but after watching them for just a few seconds i saw that they were swimming around and moving !!!They are very tiny and all white, does anyone know what they may be and if they are harming my fish in any way?
Probably bug larva. It sucks because this will kill your cycle but get the betta out and clean the tank fully, everything, with hot water and vinegar. Rince the tank a few times. Then give your fish a salt bath to make sure none of them ar eon your betta. That should get rid of them as long as you clean EVERYTHING(gravel, decor, filter etc etc).
could be hydra's or if they look like a small worm planaria. If you use google you can see some pics of both pests... If the tank is small it's probably best to clean it, but you can keep the water though...
popeye is a bacterial infection in or behind the eye of the fish and can occure when the immune system of the fish is weakend by something like bad water quality, stress and so on. If it has something to do with the white critters in your tank i don't know for shure, but i don't think so.