I have been stocking Tilapia in my two ponds every year for over 10 years. (The hardiest species, Blue Tilapia, die when the water temp gets down to 45-50 degrees, hence the annual restocking.) They are excellent at eating filamentous algae (aka pond scum), but will not eat leafy/stalky plants like arrowhead or floating leaf pond weed. If present in high numbers, they will eat fish food.
I find them to have little taste or texture compared to what I consider "good eating" fish (bluegill, walleye, etc.) But at least I know the ones from my ponds didn't live in Chinese sewage like a lot of imported Tilapia
