Duckweed’s Nemisis

[TomO]

I have about a dozen variatus platties in a 30 gallon. I also have duckweed that covers the entire surface, so much that it makes feeding difficult. Besides goldfish is there another fish I can put in my tank that will be cool with my beloved platties and will devour the duckweed. My parrotfish will eat it if I net out a bunch from the 30 and drop it in the 75.  But in a month I’m back to square one in my duckweed battle.

[Fish Folk]

Nothing foolproof. Mature Goodeids will sometimes eat duckweed. Incompatible with Variatus, African mbunas chow down on duckweed.

One possible solution is to majorly increase your surface flow. Duckweed does best with no flow. Add a spraybar or heavy HOB turnover, and it will struggle.

You can spend daily diligence for one month, and possibly crush it.

Or… just give up.

Like I did.

😎 

[TheSwissAquarist]

On 12/18/2022 at 10:41 AM, TomO said:

I have about a dozen variatus platties in a 30 gallon. I also have duckweed that covers the entire surface, so much that it makes feeding difficult. Besides goldfish is there another fish I can put in my tank that will be cool with my beloved platties and will devour the duckweed. My parrotfish will eat it if I net out a bunch from the 30 and drop it in the 75.  But in a month I’m back to square one in my duckweed battle.

Sorry to break it to you, but you have no chance at beating duckweed. 3mm plastic mesh can help scoop it off the surface though.

I gave up a looong time ago!

[Guppysnail]

Not fish but mystery snails. Mine will sit at water line and eat for days. I intentionally use duckweed in all 12 tanks because my tap is high nitrate. The only tanks I can maintain anything more than some duckweed floating about are the ones with no mystery snails. I moved them out of one tank to a new tank and within two weeks I went from a consistent sparse few swirling in the middle out of snail reach to a beautiful covering. 

[PineSong]

I am here to represent the hope that you can vanquish duckweed! 

I began an experiment with getting rid of it from one of my tanks, back in October. As you describe, @TomO, my duckweed was so thick that food I tossed into the tank in the AM might still be sitting on the surface of the duckweed when I got home from work nine hours later. That's too much.

Below is the link to my process. As of today, about six weeks after I started, I consider it a victory--not only from the original tank, but I used the same method for my other tanks as well. I believe the key was dropping the waterline, removing all floating plants and trimming back plants like corkscrew val that reached the surface so that the whole surface area of the tank is open for netting of stragglers. Daily checks with the air pump/filter turned off so that no stragglers were disguised by surface agitation, and extra-double dog cleaning of nets between uses.  After a few weeks I got sloppy and used a net in my tank that had recently been in my pond--voila! a couple of duckweeds a few days later. I had to remove all the frogbit again and go back to daily checks with the pump off.

But as of this moment I am duckweed free in all of my tanks except the pond and the emergency goldfish tank I set up yesterday with pond water.