Tilapia are carnivorous from the day they are release from their mother's mouth until the get about 4 or more inches long...then they start leaning toward vegetation...duckweed, algae and other aquatic plants and debris.

If your Tilapia are of that age, it will do the guppies not good to group and they won't last long enough to reproduce to replenish their selves either. They'll be history in a short - short.

I doubt you could even raise enough guppies in a separate tank to ever keep the Tilapia's appetites appeased so start looking for a source of floating catfish or KOI food to feed them once. Even if it's too big for their mouths, they will suck at it as it softens until it is gone then they'll go looking for more.

OH...and "PUT DOWN THAT NET AND STEP AWAY!"