Preheat your grill — medium-low heat on one side and high heat on the other side.
To mince the herbs, you can do this by hand with a chef's knife, or place the herbs, zests and olive oil in your food processor and give it a few whirls.
Pat fish dry with paper towels, and season both sides with salt and pepper. On a large plate, mix together the chopped fresh herbs, lemon, orange zest, olive oil and a little salt and pepper.
Generously coat both sides of the fish with the herb mixture and allow the fish to marinate for 10 minutes. Place the fish over the medium-low heat side of the grill, cover and cook for 4 minutes. Flip the fish, cover and cook for 4 minutes more, or until the fish flakes easily when poked with a fork. Just before serving, squeeze a little lemon juice or orange juice on top of the fish.