ID? Tiny water cover

I have a section about 18 inches around in my pond of a tiny plant that is growing almost like a mat, just on top of the water. It came in on a water hyacinth. Is it a weed and should I get rid of it? Have any ideas?

Duckweed maybe? http://davesgarden.com/pf/go/1987/index.html

I can't keep duckweed in my ponds, the gold fish love to eat it.

:^)))

Or perhaps Pacific Mosquito Fern, Fairy Moss, Water Fern (Azolla filiculoides)
http://davesgarden.com/pf/showimage/38537/

Thanks for the info...I think it's duckweed. I just keep scooping it out so it overtake the entire surface of my small pond!

This thread is so old, but I wanted to say that I can't keep duckweed in my pond either, but I live near a natural wetland and keep replacing what my fish eat that way. I believe duckweed is an excellent oxygenator, very good for the pond ecosystem.

The benefits of duckweed are that it eats nutrients that algae might eat and that it blocks light. Duckweed is a poor oxygenator. If you want a good oxygenator, try hornwort or anacharis- but if your fish are eating duckweed, they'll probably eat those, too.