Duckweed can be used as feed for Tilapia and many other animals on the urban ranch. My rabbits and Tortoise will eat it. It is very high in protein, easy to grow and grows very fast.
I say easy to grow but you have to provide it with the proper conditions. I was not successful with my first attempt. I, of course, looked it up on the internet and thought I had a clear understanding of the process. I felt very fortunate to find a local nursery, catering to city farmers, that had two kinds in stock. I loaded some plastic tubs with tilapia water, placed them on shelving against the south east side of my house and watched nothing happen. It didn’t die, but it didn’t grow the promised doubling every 2 days either. It just sat there. I waited and waited.
Finally I asked the nursery owner what the secret of growing duckweed was. He said,”wellll, it likes shade and fish poop”. And that was that.

I went home, hauled my tubs around to the north side of my house. I attached window screen on top because I was becoming concerned about mosquitoes and the duckweed took off. They got filtered morning sun and that was it. I have since moved them back to their original place purely for convenience but now they are covered so they only receive filtered light.

Interestingly, I expected them to grow until they covered the surface of the water. They do in fact prevent mosquitoes from breeding in the water because the mosquitoes can’t get to it. I didn’t expect the duckweed to grow and grow until it formed a layer at least a half inch thick floating on top of each other.

Now to feed I just run my cupped hand over the surface of the water and wind up with a handful of duckweed that I chuck into the tilapia barrel/tank. I have heard that some tilapia are resistant to eating anything but there regular feed. My experience suggests to include weed with the normal feed. Mine are such enthusiastic eaters it all gets eaten. And sometimes I just give duckweed. If they don’t eat it they don’t eat.