Aquaponics - Duckweed


I finally got hold of some. I've been looking around for it for ages, but all the plant stores stock a plant that isn't really duckweed. Every single nursery I've been to has assured me over the phone that they stock the real deal, but have all turned out to have something else.

I guess I should mention that the reason I wanted the stuff is because fish eat it. Its a great way to get rid of excess nutrient, and is also a useful feed because it floats so doesn't get sucked into the pump before the fish get a chance to eat it.

It looks like this. At least I hope it does. All plants look the same to me.

Duckweed has some claim to fame. I'm told it produces the smallest flower. But I wasn't told it makes three of them, so I guess there is good reason to doubt it's record holding status as well.

Who knows.

I have duckweed.

As far as I can tell duckweed normally reproduces asexually by dividing into two leaves. If you look at the picture, you can see some leaves almost look ready to divide. Many of the leaves have two roots extending ten or fifteen millimetres into the water. I'm guessing when the leaf decides into two, each half gets a root. I'm told that it also does the pollination thing from time to time, but who knows.

I have duckweed!

I put some into a large container with some fish emulsion as fertilizer. After a day or two I noticed an oil slick, so I  added an air stone attached to a small fish tank air pump. The slick cleared up within a few hours, and the duckweed took on a healthier shade of bright green. I know there isn't a lot of science in that, but I'm guessing duckweed needs oxygenated water. I was hoping to just keep it in a container of water with a large surface area, throw in some goat dung, and leave it to it's own devices, but I don't think it's going to be as simple as that.

The plan is to use the original planned growbed with pvc edge capping for a duckweed plantation. The growbed was too easily scratched to use with gravel in it, but filled with only water and duckweed, it should be fine.

I kept it for five days before giving it to them because I was concerned the pond it came from could have had some diseased or parasite infested fish.

I only know a small amount about one fish ailment other than poison plants, and that is a parasite called Ich. Ich is a fish parasite that can't live away from fish for more than three days, so at least my five days should prevent it from being an issue.


  1. This Duck week seems like amazing stuff, you said it was hard to get the correct plant. where did you find it in the end... is there a scientific name it goes by to better identify it?

    Fantastic blog by the way!

  2. I got it from a plant store. Actually a friend found it for me. I think he got it in Glenelg, South Australia.

    Its real name is Lemnaoideae and comes in various forms.


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