unknown bugs

[emi-chan]

I don't know if I'll get a response, I haven't been on the site for ages but I can't find anything that looks like this...
I have bugs in my tank. These bugs to be precise:

IMG_3238

what the heck are they? I have a 150l freshwater tank with three mature weather loaches.
water parameters are normal....
I've never seen these things before!
they hang out around the water line and flick on to the surface of the water every so often.

[Bas Pels]

I would think Asellus aquaticus, for which Wikipedia has the following Engils names waterlouse, aquatic sowbug and water hoglouse.

Looking further, it does seam to be harmless, and good food for fish.

Obviously, being Dutch, that is not native in English, I started with the Dutch name - and than Wikipedia provided a parallel page in English. THis is by far the easiest way to translate the names of species - dictionaries normally don´t have them.

[jonstfrancis]

They are above the water-line it seems.
They are springtails of some kind (Collumbola) by the looks of them. Harmless, they are feeding on grime. If you don't want them there then you simply need to clean the area around the top of the aquarium. They can't live under the water.

As to fresh waterlice (Asellus aquaticus) , they grow quite big and can be a serious pest and will even kill and eat small fish. Although larger loaches will gobble them up with relish.