temp should grouper fillets be grilled to
Step 4. Place the grouper fillets onto the hot fish grate. Let the grouper grill for three to four minutes. Slide a spatula beneath the grouper fillets to turn them and grill for an additional three to four minutes, or until the internal temperature of the grouper reaches 125 to 140 degrees Fahrenheit.et the grouper grill for three to four minutes. Slide a spatula beneath the grouper fillets to turn them and grill for an additional three to four minutes, or until the internal temperature of the grouper reaches 125 to 140 degrees Fahrenheit.