Probably washed in from a pond that was stocked in the watershed. We have stocked tilapia in our ponds for 10+ years now. Last year was the first year they did not all die in the winter. Even with the mild winter we had last year, just the males survived. Don't hold your breath on them surviving the winter. Outside of a power plant lake, they will not live through the winter most years.
Come to think of it you made a good point. We used to live in sunset point in little elm. There are some ponds/canals that eventually dump into the lake. My wife caught a nice tilapia under a bobber there about four years ago. I guess someone or the HOA stocked them. This could have come from there. The canals flood every time it rains and wash fish into the lake.
