I have not tried it, but here's the grilled recipe. The link also has 3 other recipes.
"Grilling Piranha Amazon Style
Grilling fresh-caught fish on an open fire is always a tasty way to enjoy a fresh catch. Use a whole cleaned and scaled fish, rub it lightly with oil, season it with salt and pepper or other available spices, then place it on a grill, about 4 – 6 inches from the heat. In the wild you can use a framework of small twigs and shaved saplings to position the fish over the fire. Cover the fish with a banana leaf (or foil), and cook until the fish is brown on the underside, approximately 6 - 8 minutes. Turn the fish carefully and continue until the flesh near the bone is (check with the tip of a small knife or long fork), in approximately 8 to 10 minutes. Smaller fish usually work best using this method, especially in the jungle.
Modifying these procedures slightly will allow you to adapt them for use with a barbeque grill. If you haven’t already, be sure to read the article “Piranha: Deadly and Delicious” which is online at: http://EzineArticles.com/?id=72722 . Buen Provecho!"
From the difference between how GOOD wild trout taste and how AWFUL stocked trout tastes I can only imagine a tank raised fish would taste HORRIBLE, and could possibly give you all sorts of problems (parasites, chemicals, yecchhhh!).