It's not water or lime spots, I do know what those look like, since we have pretty hard water up here. I ALWAYS wash my hands before putting them in the aquarium and in between aquariums. It's not the duckweed, and these are like all evenly spaced. It's weird. Have you ever seen sea lice on a salmon? They are shaped kinda like that, like a head with a tail, and the "tail" waves with the water. There is nothing in my aquariums that are not aquarium safe, I am too paranoid about that

. The only thing I have in them that was not from a store, is glass. A bowl I made and some beach glass, which has all been cleaned.