Backyard Aquaponics
A place to discuss aquaponics

I put some small goldies in a 380ltr duckweed tank and they cleaned up the duckweed in a couple of days.

When I put the tilapia into the tank, the solid cover of duckweed persisted for a week or so before it started to thin at all.

Takes them a while to work out its food. I have small goldies in with 130 fingerlings that I feed fish too. The goldies get flakes until they worked out that minced fish is yummy. These were the same goldies that worked out duckweed was food.

Hum, perhaps I'll have to put a divider in that tank to keep the fish in one end and allow the duckweed to grow in the other and see if it comes back. If it does come back I will know how much duckweed it really takes to support several tilapia.

If it is disappearing, then the fish are probably eating it. Because when it dies, it turns white. <grumble>

I was rather expecting that the growth of the duckweed in this big a tank would be able to keep up with the grazing of 4 tilapia. So, apparently something in the conditions is not good enough for the weed type growth duckweed is supposed to be known for. The location gives good morning through mid day sun but I have covered the tank with 75% shade cloth so it is getting bright diffused light.
Nitrate is still at around 40 ppm. There is little to no ammonia showing in the test and the nitrite is a .25. That system has plenty of salt in it and has been getting maxicrop. The tomato and cucumber plants in it seem to be growing quite well and the mint up top is finally coming back after being ripped to shreds and left to drown for several days.

I suppose I could add more tilapia to the duckweed pond for the summer if I need to do any big changes to the big system or I could just leave it along and see what happens for a while.

Tc,,, Duckweed feed rates are usually given in dry-form. So grab 10% of your duckweed , let it dry compress it and you will get an idea how little food it really is. Estimate your Tilapia stomach size ,, they fill 3 times a day and with 4 fish will need 12 times that amount..........That is a LOT of duckweed ....., this is why many studies have found growing duckweed as fish food is just uneconomical. Having said that ..... it is uneconomical in a pond that just has a single surface grow area,,, I have always wanted to trial and net flow system ,, a long net that moves in and out of the water ,, ()()()() up down in out ,, if the duckweed will stay on the net it will give many times the growing surface for the same AMOUNT OF POND SPACE ....., i THING THIS IS USED FOR ALGAI GROWTH IN INDUSTRY?

I expect that to grow enough duckweed to be really useful, I would probably need to set up trays for it like the fodder shed model where the trays could be on racks (since duckweed doesn't need direct light) which would provide much more surface area to grow it.

But there are plenty of other things keeping me busy right now to that idea will have to wait.

when this article say "fresh duckweed" does that mean undried duckweed?

http://www.businessmirror.com.ph/compon ... ushed.html

The protein levels are for dried ....., it's 90% water
Amazing paper ,, the results go against hundreds of other studies ..... ROFLMAO
I suggest someone high up in the Phils governemnt owns a lot of land with duck weed ponds ..... next they will probably say it contains GOLD .. perhaps even DIAMONDS,.....,,

Suggest a bit more reading and reseach may give a more balanced view ( perhaps even the truth).

The internet is a wonderful source of information , but don't believe everything you read.

at least 10 times protein per an acre than corn... hey that's pretty good.

http://www.miller-mccune.com/science_en ... kweed-1175

Is duckweed salt tolerant?

from what i gathered, they are not salt tolerant.

chappo - here's another study that agree with the finding of the first link i posted.

http://md1.csa.com/partners/viewrecord. ... cookie=yes

someguy ,, OK no worries ,, as they say GO for it. I grow crops of Tilapia in the tens of tons ,, but I obviously missed something.

When you are growing processing and selling this wonder product /.....,That makes me wonder why it hasn't already been done??? ,, But when you have your private island house , personal jet etc , all I ask is a weekend holiday once a year .

Sorry for the sarcasm , but been there done that,,, I would be happy if you proove me wrong , but I doubt it.

Just so you get some balance from information , here is a link that prooves the earth is flat http://www.alaska.net/~clund/e_djublons ... ociety.htm

i didn't know information from the internet could be false. thank you for pointing that out. =]

there's 2 separate questions here.

can duckweed be supplementary to commercial feed?
i think the answer is yes. 1:1 ratio seems to be the answer.
http://scholar.google.com/scholar?q=duc ... s_ylo=2004

can duckweed be produced efficiently?
i think that depends on your resources. now, just because chappo can't do it doesn't mean it can't be done. or does it?