Tilapia DO work, they just have to be stocked at the correct amount to do the work. How many might depend on the amount of FA that you have in the pond.
In my pond, I caught a lot out when the water dropped to the mid to low 50's via snagging.
I'll let Rex come up with the numbers that he recommends to stock.
I can tell you that in my pond, I didn't see FA control with stocking rates of up to 20#/surface acre. I DID see them control FA when stocked at the rate of 40#/surface acre. I didn't weigh the fish that I pulled out, but the fish were between 1 and 3 pounds, and I filled five 5 gallon buckets with them, and there were some still swimming around. I stocked Tilapia that were 6"-8" long to avoid predation by the LMB in the pond.
