Any ideas on these bugs?

[mikeandjenn99]

So I've had a little colony of these little bugs in my tank for a while now. I can only see them in the back corner of the tank, but that's probably only because they are too small to see anywhere lese. Nothing seems to be bothered by them, but if anyone can tell me what they are, I'd appreciate it. The are about the size of the pointy end of a pin. The head of a pin is too big for them. The coralline spot in the pictures is about 4mm for a size comparison. I can see a pair of antennae on them, but can't make out legs, and they move very fast across the glass.

http://i188.photobucket.com/albums/z233/mikeandjenn99/CIMG7121.jpg

http://i188.photobucket.com/albums/z233/mikeandjenn99/CIMG7124.jpg

[rjsilvers]

Copepods.

[mrbigshot]

they are good, the clean and get eaten by many fish