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Introducing Duckweed


monster tank newbie
I might be crazy...but I'm thinking of voluntarily introducing duckweed into my 125g South American tank. I had a lovely planted tank when I first started up the tank 4 years ago (photo here), but a year or so ago I introduced some Severum to my community and they destroyed everything. I've tried java fern, anubias, other recommended hardy plants - and nothing survives their insatiable hunger for live plants. Even some floaters (frogbit and red root) didn't escape their apetites.

I've heard that duckweed is essentially impossible to kill of, so in a fit of insanity and longing for my old planted tank back, I have an urge to actually voluntarily introduce duckweed into my tank. Bad idea? Will it just ruin my life? Does it make normal fishkeeping duties annoying, like water changes and filter maintenance?

I guess what I'm asking is...do I need to be talked out of it? Should I instead be talked into moving the severums and restarting the plants?


CCA Members
Well, in theory the severus might actually eliminate any duckweed as quickly as you can put it in. Its not really damaging, and it can help a lot -- it removes tonnes of nutrients, adds shade, keeps fish from leaping out, and I also agree its attractive. Its really only a pain in the Azola if you're worried about transmitting it between tanks, in which case you have to be careful to rinse equipment and what not.

I have duckweed in pretty much all of my tanks except one or two, and keeping it out of those ones is a pain. But, if you're not worried about spreading those suspicious green dots, go for it.


Staff member
Duckweed is almost unavoidable with planted tanks. If you want plants to help with processing waste, you could always use a hang off the side refugium or a small breeder box to protect plants from your fish, or even just try hanging some pothos over the side. They'll probably gobble up duckweed pretty greedily, but it's good for them, so why not?


Former CCA member
How strong are your lights? I have some water lettuce that reproduces quickly. Maybe it would survive?


monster tank newbie
How strong are your lights? I have some water lettuce that reproduces quickly. Maybe it would survive?
Thanks all for your input (even you, Blaise :p ) If anyone has duckweed to spare I am still considering trying it.

In terms of lighting, I have two of the 6 foot eBay special LED lights, so pretty good coverage. My tank is probably too bright for the fish right now, so even more reason for plant cover. I would certainly try some water lettuce. Any issues with having glass lids?


Well-Known Member
It will probably get eaten just as fast as anything else and not be able to multiply fast enough. If you still want to try it but are still cautious about it, i have some giant duckweed you can try. its a bit easier to keep contained to one tank since its a bigger plant.


I've tried it with my insatiable plant eaters. They ate it until they wouldn't. I've found that they get tired of it and stop eating it.

Coptodon, Amatitlania, Rainbow Cichlids, also Goodied I can't recall the name of.

If it doesn't work out, you could always rig up a bottle trap. It never seems to remove all of it though. I have to retrap every other week or so.


I have amazon frogbit that grows in a couple of my tanks. I put it in my 180 when I’m doing some trimming in the planted tank. My uaru DECIMATE it, but haven’t added any since adding the severums recently. Can’t imagine it lasting with them either