Little creatures in my tank...

Ok - so I've just this minute been shining a torch on my tank (not something I normally do...) and I noticed that there were quite a few little specs on the glass, and that whilst some of it was simply a bit of grime, some little specs are alive and zipping around

They're no bigger than this --> . <--- and might have the littlest tail? I was just a little freaked out since I've never spotted them before now, and only did so because they showed up in the torch light. They're too small to photograph really, but I was wondering whether someone could tell me what they might be? There must be quite a lot of them, and the only ones I can see are on the glass.
Do I need to worry about them? Or are these little mite-things expected in a tank with live plants etc? My Axolotl seems fine. If they are potentially harmful - how do I get rid?

Thanks again you lovely knowledgeable people!

The good news is your water chemistry is in pretty good shape if you have little critters running around.

Have a look at this. It may help you identify what they are.

Most tank invaders are not an issue, so I wouldn't worry too much.

Phew! :happy:
Thanks a lot for the swift response Sludgemunkey. I'll sleep more soundly now I know! Cheers!