Duckweed should I use it?

[Chris McMahon]

I have seen a couple of videos on youtube where people are raising duckweed and freezing it into blocks. The fish really seem to like it. If it's frozen is it safe as a fish food? I don't want it to take over my grow beds.

[Carey Ma]

Hers my two cents:

I use to collect as much (wild) duckweed as I wanted from the many irrigation ditches/ canals around the village but was a little concerned about any pollutants that might end up in me so I started to grow my own

I grew duckweed in several large long beds (4' x 16' x 5") that flowed directly from the fish tank's and duck pond's solid waste filter. An air pump was attached to the outside connected to three circular air stones and placed in the bottom. A plastic platform with legs and holes drilled into it used to separate the perlite and crushed bricks (like in a wick systems). The filter consisted of air-stones, separator, perlite and crushed bricks with a layer of geotextile in between each layer except for the separator. There I used a mosquito screen. Another piece of geotextile was placed on top followed by a piece of river rock where the water splash. Worms were placed on top of the geotextile to eat up and break down all that fantastic poop.

 

From the duckweed grow-beds, water was siphoned off the bottom of the beds into a connection at the bottom of a bucket. A brick or two was placed in the bucket to deter any plants that might accidentally get in from going across the bucket and directly into the exit hole on the opposite side (idea taken from septic tanks). I simply scoped (netted) any little wanderers off (if any) and added it to the rest of the harvest.

The collected duck weed is enclosed in an old T-shirt with the holes sewed shut and Velcroed, then squeezed and spun dry, after which it is placed in the solar dryer or freezer depending on what I was doing at the time. Either way the dried material was then ground into powder to add to the other ingredients, to make feed.

 

Duck/ Fish pond > solid filter > Duckweed beds > bio reactor > grow beds 1-6 > cistern + oxygen > fish pond > duck pond

 

 

[Kobus Jooste]

Very nice set up Carey - what did you use the feed for? Only fish or for other animals, and can you tell us more about the feed itself?

Carey Ma said:

Hers my two cents:

I use to collect as much (wild) duckweed as I wanted from the many irrigation ditches/ canals around the village but was a little concerned about any pollutants that might end up in me so I started to grow my own

I grew duckweed in several large long beds (4' x 16' x 5") that flowed directly from the fish tank's and duck pond's solid waste filter. An air pump was attached to the outside connected to three circular air stones and placed in the bottom. A plastic platform with legs and holes drilled into it used to separate the perlite and crushed bricks (like in a wick systems). The filter consisted of air-stones, separator, perlite and crushed bricks with a layer of geotextile in between each layer except for the separator. There I used a mosquito screen. Another piece of geotextile was placed on top followed by a piece of river rock where the water splash. Worms were placed on top of the geotextile to eat up and break down all that fantastic poop.

 

From the duckweed grow-beds, water was siphoned off the bottom of the beds into a connection at the bottom of a bucket. A brick or two was placed in the bucket to deter any plants that might accidentally get in from going across the bucket and directly into the exit hole on the opposite side (idea taken from septic tanks). I simply scoped (netted) any little wanderers off (if any) and added it to the rest of the harvest.

The collected duck weed is enclosed in an old T-shirt with the holes sewed shut and Velcroed, then squeezed and spun dry, after which it is placed in the solar dryer or freezer depending on what I was doing at the time. Either way the dried material was then ground into powder to add to the other ingredients, to make feed.

 

Duck/ Fish pond > solid filter > Duckweed beds > bio reactor > grow beds 1-6 > cistern + oxygen > fish pond > duck pond

 

 

[TCLynx]

As Pointed out one of the challenges to formulating your own feed regime is going to be figuring out what it might be missing.  The feed companies have run trials with different ingredients and formulations and checked the fish for growth rates and deficiencies to see what works and what doesn't. 

It is that kind of large scale testing that we don't get the benefit of when we try to formulate our own feeds. Plus, we are not only trying to grow healthy to eat fish, we are trying to grow our veggies from the proceeds of feeding the fish.

 

Anyone who can share their low tech methods for making their own fish feeds, please do.

 

There are vitamin/mineral admixtures you can get for making fish feeds.

[Carey Ma]

@ Kobus: Most of my ingredients are dried and ground into powder and stored in light/ air proof containers in the fridge or freezer. Each container is marked with the name and attributes. For efficiency, I make a "premix" of the finer, more powdery ingredients, measuring it out in amounts sufficient for 25-lb. batches and storing it until use. I designed my formulas to be set up on the basis of 100-lb lots, since it is easier to think of the ingredients as percentages. However, I make up my feed in 25-lb. batches, since that is easier when mixing and is used up fairly quickly. If I can’t grow it or harvest it without harming things I resort to buying and storing anything I can for later (winter) use.

At present I make feed for: fish, rabbits, sheep, chickens, two horses and eleven to twenty dogs.

 

Fish, rabbits and chickens start out with the same base formula of around 20% protein then I add the other stuff for their specific conditions and needs but I think my actual trick is not so much making this feed but growing sprouts (grass) as fodder in winter that really brings everything together.

 

By emphasizing the percent protein in the tables, I do not mean to imply that the other major and minor nutrients (fats, carbohydrates, minerals, vitamins, enzymes) are not important-certainly they are. I have worked with complex formulae to determine the correct balance of the various nutrients, and discovered that-when making feeds from whole, natural ingredients as I largely do-the balances come out right if I simply peg a given formulation to the protein percent needed. If I were using a lot of processed or byproduct ingredients, of course, the calculation would become a good deal more complicated, (which, in my opinion, is where feed companies make their money).

 

A further point about protein: My feeds would be considered short on protein slide by designers of poultry feeds. For example, the recommended percent protein for broiler chicks is 22%, I believe, and you will notice that my Starter Mix may be around 17.5%. I am not growing one of the suped-up, fast-growing hybrids such as the Cornish Cross, nor am I growing broilers for a market. For traditional homestead breeds, however, I'm not sure it's a good idea to "push" growing birds for maximum rate of growth. It may be that best long term health and reproductive success are achieved through a growth curve which is somewhat slower, but more balanced.

 

In my opinion fish food has defiantly, been a challenge compared to the other feeds due to processing variables.

 

@TCLynx: Yes whatever your fish get, you and your plants get in return. First off I don't trust those big companies to have my best interest at heart. Purina killed my dog (a long painful death) with melamine; knowing that we love our pets like members of our family, you would think they would have a bit of heart, so what do you think they think about some slimy fish? (Sorry, I got a bit emotional).

Ok. Commercial feed is much cheaper and easier for meat producers to use. But the truth is, if you are feeding commercial feeds, you are taking part in the most radical feeding experiment of all, one designed to answer the question: Just how unnatural a feed they can get away with? Again. All big companies care about is their bottom line! How much will they make? Whatever is the cheapest way to minimally satisfy their customers without being sued.

Contrary to all advice from my colleagues at the Ag colleges, the lab-coated livestock nutritionists, and all other recognized experts in the field, granny simply threw a little kitchen scrap and scratch grains to her birds once a day (more to keep them fixated on the coop as the place to return home than for nutrition), and allowed them to free-range over a 85-acre farm. This apparently haphazard approach allowed the chickens to mostly feed themselves-the way chickens would have fed themselves before man domesticated them. Following in my family’s footsteps I use both traditional wisdom and modern science to farm.

I know we are talking about fish feed but I think the same principle kind of applies. I believe that if we stick to whole, natural ingredients and peg the proper protein percentage, everything should turn out fine and if you still worry that not everything is in that soup, you can have the water tested and add the appropriate salts as they do in pure hydroponics.

As for low tech methods that are easy, cost effective and sustainable…I too would like to know.

 

[John Allison]

Where can I get Duckweed in the Philippines?  I live on an Iland an dI am not sure if it grows there.  Can anyone give me help in this area?

[Eric Warwick]

I think that duckweed is best of for commercial systems where fish are grown-out quickly, to do this I'm sure they over-feed the fish, and the duckweed will keep the ammonia on the low side and help the bio-filter from being over-whelmed and dying.

However, waste—not human—transformation, similar to a compost pile, could be a use for duckweed. Plant scraps and other garden biomass can rot in a stagnant pool—perhaps a kiddie pool—essentially  a compost pile for your fish. 

[Carey Ma]

@ Eric: I don't think a stagnant pool of rotting anything is a good idea because it may contain pathogens. I always use oxygen where ever I can to lessen the chances..

[Eric Warwick]

True... your point?

Carey Ma said:

@ Eric: I don't think a stagnant pool of rotting anything is a good idea because it may contain pathogens. I always use oxygen where ever I can to lessen the chances..

[marty lininger]

did this discussion ever happen?   i am looking but not finding it

i am very interested in duckweed production

Harold Sukhbir said:

Hi TC,

I'm with you on this! Would you like to start one? Kobus is doing a lot of work here and it will be good if we get some serious minded folks involved. We have work ahead, this is not really a time to take it easy, I for one am very interested in the area of algae growing.

TCLynx said:

Would probably be worth starting another thread perhaps over in the feeding group to explore how to grow one's own foarage for the fish the way people do such things for their free range flocks or the way farm ponds are fertilized to encourage fish growth.

[TCLynx]

There are lots of duckweed discussions going on.  Too busy to go find them right now though.

[Ron vanDyk]

I have seen duckweed on sulit.com in philippines

there we live near dumagette and have some

Chris McMahon said:

The duckweed I ordered on ebay died in my mailbox. I guess 111 is a bit too hot for it. I better try again when the temp gets a bit lower.