I'm pretty sure there are plenty of posts just like this on the forum but I didn't see any pictures that looked quite like what I have when I searched around.
That being said, I have a 2.5 gallon tank with one betta, a couple of Amazon Swords, and a Java Fern. I have a Whisper 3i filter, and a small heater that hasn't quite been working.
I'm on spring break and didn't want to leave Demyx (my betta) at school so I brought him home via subway and train. I know. Stressful. Probably more so for me than for him. But it was a rainy day and I suspect a few drops of rain may have landed in his tank on the way. That being said, two days later, I went to my local pet store (way cheaper than city pet stores) and picked up some blood worms (which he loved) as well as one of those floating betta logs (My mom decided she was going to spoil him). I was eager to add it to the tank, so I washed it down in hot tap water let it cool and added it to the tank. After my fascination with where it would float in the tank faded, I started to notice these little white dots. All over the tank. I mean ALL OVER. Thousands it feels like. They were floating in the water, and all over the walls. I decided it wasn't dust when I started observing their movement patterns on the walls, which seemed to not be affected by Demyx swimming by, but would reverse if they crashed into each other. With the filter on, the number floating in the water seems to have diminished, but the number on the walls has not changed. In fact, there is one section on the wall that had a high concentration yesterday, and today seems to have that same concentration but with an equally large concentration of equally smaller white dots. My parents think I'm crazy saying they're moving. I assure you, they are. I've attached a picture so that you can see what I'm talking about. The black line in the background is the width of your average power cable (it's from the heater). Is it really just copepods or could it be something worse? Could I do anything to get rid of them? I should note also that the temperature the tank is being kept at home is 72-74F, whereas because my dorm at school was warmer, the temperature there was about 76-80F.