LoopTech,

If you provide any kind of artificial feed in the pond with Tilapia, it may reduce their effectiveness at controlling FA and duckweed...and the effectiveness reduction can be significant (up to 70%) depending on how much artificial feed is provided.

Duckweed can be controlled by Tilapia but you need stocking rates much higher than we normally use for FA control and forage production. All situations are different, but generally about 30 pounds per acre has been found to be successful for duckweed control by Tilapia in our area.