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Is it possible to reproduce Duckweed along with Tilapia in an IBC tank? Goal - Lowering ammonia & oxygination with DuckWeed, while avoiding over feeding.

I could not make the duckweed proliferate in my Tilapia tank. They would not give it a chance to thrive if it was placed in their tank. This made me ask myself: What would happen if I added an abundance of duckweed in my Tilapia tank?, Would they feed on it endlessly until their deaths? Would there be enough surface area in my IBC tank for the Duck Weed to thrive along with  110 Tilapia?

I also heard that I may need a larger surface area to enable more Duckweed growth perhaps implying a shallow Tilapia tank or having less Tilapia per gallon? It sounds to me that the only way to have a constant supply of Duckweed for Tilapia may be in conditions of a shaded shallow pond with a low or moderate population of Tilapia.

My aim is to make the Duckweed lower the ammonia and oxygenate the fish, and so far I may have achieved this to a a degree by keeping the Tilapia from reaching the Duckweed yet sharing the same water. Possible benefits are:

  • It may even bring down you electricity costs because you can use smaller pumps to oxygenate and clean the water.
  • It could be a passive way to keep the fish alive if you lose your electric power.

I know Tilapia, given a choice, like to vary their diet; but I just don’t know if they would stop eating the Duckweed after a certain point. My guess is that they would search for something else to feed on after they get their fill on the Duckweed; and they would not overfeed to death. But it’s just a guess I really do not know. Has anyone tried to reproduce Duckweed in a Tilapia tank that could help answer my questions?

 

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I've written lots of posts about duckweed.  Unfortunately I never seem to have time to go searching for them to link my repeat answers.  So I finally wrote up a blog post on the subject.

TCLynx on Duckweed

Well, none of mind ever died of overeating duckweed.  When I was feeding those 12 a small hand full (perhaps 1/6th of a cup) of commercial pellets per day they didn't eat much duckweed.  They only cleared out the duckweed when I didn't feed them for days.

The feeding behavior in a heavily stocked tank will be different of course, I've noticed a tendency in a heavily stocked tank for tilapia to eat or try to eat everything while in a tank with only a few tilapia you almost never see them eat.

I read your blog post : "Aquaponics, Tilapia, and Duckweed" Great post!

TCLynx said:

I've written lots of posts about duckweed.  Unfortunately I never seem to have time to go searching for them to link my repeat answers.  So I finally wrote up a blog post on the subject.

TCLynx on Duckweed

Best to grow your duckweed in a separate area, and then feed it to the fish. We feed duckweed along with pellets and use the floating duckweed as an indicator when the fish are hungry again. They eat pellets first, then graze on the DW.

I saw the same behavior (regarding a low populated tank), they seem to be shy eaters when in low concentrations. Great feedback, thank you.

TCLynx said:

Well, none of mind ever died of overeating duckweed.  When I was feeding those 12 a small hand full (perhaps 1/6th of a cup) of commercial pellets per day they didn't eat much duckweed.  They only cleared out the duckweed when I didn't feed them for days.

The feeding behavior in a heavily stocked tank will be different of course, I've noticed a tendency in a heavily stocked tank for tilapia to eat or try to eat everything while in a tank with only a few tilapia you almost never see them eat.

How did you come up with that?; that is an awesome idea! I love it and I'm going to try it. Thank you Sheri.

Sheri Schmeckpeper said:

Best to grow your duckweed in a separate area, and then feed it to the fish. We feed duckweed along with pellets and use the floating duckweed as an indicator when the fish are hungry again. They eat pellets first, then graze on the DW.

I want to thank all of you for you help in understaning Duckweed and Tilapia, TCLynx and  Sheri Schmeckpeper thank you, you where very helpful.
 I just found some extra info on Duckweed just in case anyone is interested: 

Learning about DW from others (like TCLynx) and experience. :) 

Here's one idea that might work if you want to grow your DW with your fish--

Suspend a bucket, pan, or tray in the water with the edges above the water line but the bottom below it. Put holes in the bottom and/or sides a couple inches below water level. Make the holes large enough to allow water to flow through the container, but too small for the fish to enter. This will allow you to grow your DW in the bucket while protecting it from the fish; then you can pull DW out as you wish.  The container shouldn't be so large that it blocks surface aeration, though.

You're doing some great research!

Carrero said:

How did you come up with that?; that is an awesome idea! I love it and I'm going to try it. Thank you Sheri.

Do you already have a Floating-Duckweed-Enclosure (such as the one you suggest) in your Tilapia tank? This idea had crossed my mind as a way for small fry to hide from adults; as well as a passive solution for lowering fish waste toxins and keeping oxigen levels up given a power failure (We get lots of power failures in PR). Turned an old UPS (uninterupted power supply) into a power backup so when the power goes out I have a few hours of electrical backup. I hooked the battery to some photovoltaic panels and a windturbine. I also invested in a 12volt pump and 1.5 volt air pump.

I'm impressed with your creative solutions to solve these Tilapia challenges, Sheri, thank you for sharing your insight. I only wish to return the favor with some idea that could help you. But it looks like that is going to be hard to do because your miles ahead of me. I'll try my best.  :)

We use a separate tray (actually, many of them because we sell the duckweed...here in the AZ desert duckweed is like gold). The trays are a few inches deep and the water is pumped into them from the top with water from our fish tank. The drain is the standard hydroponics drain that sits on a standpipe, so the water is always a couple inches deep. I cut the bottom out of a plastic cup and put it over the drain, with holes in the bottom so water can go through below the water line, but duckweed can't go through. That made a barrier so the duckweed rarely gets to the actual drain & doesn't stop it up. This provides the DW with fertile, well-aerated water.

Wow do you have pictures of that?

Sheri Schmeckpeper said:

We use a separate tray (actually, many of them because we sell the duckweed...here in the AZ desert duckweed is like gold). The trays are a few inches deep and the water is pumped into them from the top with water from our fish tank. The drain is the standard hydroponics drain that sits on a standpipe, so the water is always a couple inches deep. I cut the bottom out of a plastic cup and put it over the drain, with holes in the bottom so water can go through below the water line, but duckweed can't go through. That made a barrier so the duckweed rarely gets to the actual drain & doesn't stop it up. This provides the DW with fertile, well-aerated water.

Here are a couple shots. These are upside-down shelf units.

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