I cannot speak for Fender's Tilapia, but a commercial fish farm near me stocks (and sells) Tilapia that are something like 99.9% male. Having just males in their RAS systems gives them he best growth rate.
Even with a proven breeding population, in past years, I have seen many more dead adult Tilapia then dead juveniles at the end of the season. YMMV.
If you stock them next year, check out the threads here (there was a good one in the last couple of months) with advice for catching Tilapia. And on the bright side, "a lot of wasted fillets" is only a problem if you LIKE eating Tilapia (personally, I think they have no texture and no taste, but that is a feature rather than a bug for Tilapia lovers).
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