How long do you cook talapia on the grill?

Generally, if you're cooking under 3000 feet, a 2-4 oz piece of tilapia that is 1/4-3/4" thick can be cooked at 350 degrees for 30-35 minutes. If you're cooking at a higher altitude, you might want to increase the heat a bit and cook for less time so it doesn't get dry. For thicker pieces reduce the heat to 300 or 325 and increase the time. When you try for the first time, definitely start fresh, so that if it's slightly undercooked you aren't risking getting sick (which is rarely much of a concern). Preheat the oven to 325-350, depending on how good you are at watching it. Start checking the meat after about 20 minutes, checking the side and the middle. By now the side will be completely white and not at all transparent, and probably a bit flakey and the very edges will be starting to crisp/dry out a bit. Check the middle. If you like it "rare", it's probably about done. This is entirely to taste. Some people like fish totally cooked and dry, so you might want to keep it in another 10-15 minutes.