I think this plant is used on ponds but I was curious if anyone ever used it in an aquarium. It's really cute - tons of tiny leaves floating on the surface.

(I saw it for sale on e-bay)

Not I

Duckweed will over power you aquairum if you put it in. It is very hard to get rid of and could clog your filtering system. Even though it is very healthy for fish, you will have a hard time trying to control it. I will grow to cover the complete top of the aquarium expecially if you have a grow likght or full-spectrum light. When I can, I will show you pictures of a pond on Green Bay, WI that was overtaken by Duckweed. Also, you will also want to make sure that the duckweed is free from parasites. I would advise buying it from a plant breeding place because they wild carries diseases and flukes.
I will tell Fu to get on here and explain more if you like.
My personal advice, is not to use it in your aquarium, when it grows, you won't be able to see your fish from the top. Also, mind you, that some fish may not eat the duckweed. You would be taking a chance to enter duckweed into your aquarium.
Hope your experience will go well.

Thanks AstraFaerie

I think I'll stay away from the stuff.

You just may want to do that. An alterative if you like, would be to grow duckweed in a separate container and you can feed your fish a single duckweed. That should not contaminate your aquarium at all. It wouldn't be a bad idea at all either. As I said before, duckweed is very nutrition for fish.
If you were to do this optiona, make sure you don't use any pesticides or fertilizers on the duckweeed. Even though it will help your turn-out of duckweed, it could poison your fish and eventually kill them.

I got some of that duck weed from Ebay, the purple kind, I believe they call it Azola? I grow it in a separate kiddie pool out in the back yard, and take a handful out here and there and toss it into the koi and goldie ponds. That is gone the next day. I like that special plant because it turns purple when it has enough sun exposure! I also have the regular duck weed. I got that from a nursery which had their whole pond covered in it (no fish in it, though, just ducks). The owner let me have a cup full of it. That cup full turned into a little pond full!
They do clog filters easily, but with growing them separately and feeding only a tiny bit to your fish you should have good success....

Right now I have a tub with ADF's in it and I am growing duckweed in it for cover and to help purify the water and keep it clean.Duckweed is excellent at purifying water and keeping it very clean.Although it cannot be kept with submersed plants because it will grow so dense as to block out light to any other plants that are below the surface.It is also very messy sometime when you have to stick your hand in the water for any reason.It is also very easy to cross contaminate duckweed into all other aquaria eventually.It is as nutritious as soybeans anmd has about the same amount of protein by dry weight and it definitely can be very useful.Many advanced aquarists swear by its ability to purify water and help keep it clean.It is best used on tanks,tubs or ponds that dont use waterfall type filters as it can push the plants under and let them get sucked up by the filter.

See, I told you he would have something to say about it for you. He's usually always got some way of helping.

I have had what I used to call "duck-weed" in my garden pond. I found out that it is actually Azolla Pinnata, a type of floating fern. (Check the name out on the Internet) The gold-fish fry love it.(To hide in) For several years I made the mistake of thinning the Azolla by scooping it out of the pond when it got too thick and using it in the garden for mulch. I later discovered that the gold-fish fry like to hide in it away from frogs and their own kind. I now scoop any surplus into buckets of water and have saved (and grown) several dozen Comet fry as a result.
I also have some in my aquarium, but I need to check my filter every day as the long strands will clog it up very quickly. It seems to be very helpfull in keeping the water clear.It does not like strong sunlight, it tends to turn purple and die, but loves the shade and will grow a lovely pale green in these conditions.

I give some for my goldfish to eat they love it/

pond taken over by duckweed:

http://www.rictus.com/viz/photos/nature/fr...og-duckweed.jpg

Wow, thats actually a beautiful picture! And thats also exactly how the pond looked in the nursery where they gave me some of the duck weed.....
Here in Florida its considered weed. I wonder why?