I have twice grown duckweed in outdoor aquaponics tanks. In the first, the fish ate exclusively duckweed, but the duckweed grew so fast I had to harvest half of it every 3-4 days. The second time, the duckweed seemed mostly in balance with the fish who constantly ate it. I have used three species: spirodela, lemna minor, and trisulca. The first time, by the end of the summer...