How to grow organic duckweed for free fish food in aquaponics. I use a raft system to grow duckweed in the same ponds and tanks that my Tilapia are in. Get more from your aquaponics system when you grow your own FREE organic fish food. Aquaponic duckweed is a very good choice for feeding Tilapia and lots of other fish. High in protein and dietary minerals, duckweed is a sure choice for good free organic feed. Cheap DIY duckweed rafts that takes a few minutes to make. Rafts help cut down on algae and help hold in heat on cool nights. We also take a look at aquaponics settlement tank draining in duckweed beds and growing duckweed in a kiddie swimming pool. Chickens love duckweed and some of your other animals may take a liking to it as well. Watch and enjoy