NOTE: Ingredients for a changed serving size are based on a calculation and are not reviewed by the author or tested. Please also consider scaling up or down cooking containers as needed.
COMBINE the tilapia, oil, lemon juice, lemon peel, oregano, salt, and pepper in a large bowl. Turn the tilapia to coat and let stand for 10 minutes.
HEAT a ridged grill pan coated with cooking spray over medium-high heat. Remove the tilapia from the marinade and sprinkle with additional salt and pepper. Place the tilapia on the grill pan and cook until the fish flakes easily with a fork, 4 minutes per side. (Cook the fish in 2 batches if necessary.) Transfer to a serving plate.
MEANWHILE, prepare the rice according to package directions. Transfer the rice to a bowl and stir in the parsley. Divide the rice among 4 plates and serve with 1 fillet apiece.