Vid: https://youtube.com/shorts/c8k_9pmGh0E?feature=share (you may have to adjust the quality to get a better view since YouTube defaults to 240p)
There are thousands of tiny white creatures in my tank that I thought were just specs until I noticed them moving today. They move like mites or tiny insects, and do not have antennae or extensions like amphipods or copepods. There are also tiny, thin worm-like creatures as well, but their numbers aren't nearly as high as the white specs.
The white specs seem to walk/crawl across the glass while the worms seem to wiggle across it slowly.
I had this same problem a few weeks ago and I cleaned out the entire tank, sterilized with boiling water for about an hour, and let it dry outside in the heat to kill anything that remained. I put my Betta in a different tank (after giving it a rinse) that I sterilized the same way (just in case) all with new plants, decor, and substrate, but a few weeks later they've appeared again.
My Betta has had this white growth above his head for some months now (seen in the video), and none of the medicine that I've used (Pimafix and KanaPlex) has been effective, so I just decided to let it go, and he seems to be living just fine (he also has this clear bubble that has appeared over his right eye a couple days ago). Is it possible that he's infected with some sort of parasite, and these creatures are coming from him? He's the only constant between the two tanks, so idk where else they could be coming from. Any help would be greatly appreciated.