CichlidFish.com - Fish That Think.

I just did a water change and vacuumed my gravel. I was watching my fish and noticed alot (thousands) of tiny things crawling around on the rocks and floating in the currents. They're about the size of a dot made with an extra fine pen, they're brown and round. They don't seem to be bothering the fish, in fact the angel is eating them as they float around. When they reach the bottom they climb down into the gravel. Any idea what these are and are they harmful? What should I get to eliminate them if they're harmful? At this point the fish all seem as healthy as always.
My girlfriend took some to school today, and the biology instructor and the environmental scientist both a that they are daphnia. Can you help me get rid of them? I bought some Aquari-Sol (active ingredient copper salt) and treated last night. Will this do it or do I need something else? The instructors suggested getting a bunch of small fish like barbs to eat them, but that's not really economically feasible.

Sorry, somehow missed your post. (Wonder if your fish try to eat them?)
http://petfish.net/daph.htm