I'm surprised by your reaction. It's a very mild white-fleshed fish with a very subtle flavor. I cook boneless filets frequently, adding a sprinkle of Penzey's Cajun or Trinidad spice or a seasoned beer batter coating. It's also wonderful in Thai and Indian curry sauces.
I suspect your tilapia was over the hill. I buy nearly all my fish quick-frozen -- it's much fresher than any I can find in local markets.
Tilapia is the very worst fish you can eat. Very LOW omega 3(good fat), very HIGH omega 6 (bad fat)