Combine lemon juice and olive oil in a bowl and stir.
Carefully add rosemary and if you have fresh basil mince into very small pieces and add. Then stir.
Once the grill is heated up oil the grates heavily with oil.
Take a fillet and dip it in the olive oil mixture covering it repeat with other fillet.
Lay fillets on grill and cook for 3-5 minutes then flip the fillets. repeat until fish easily flakes with fork or inside of fish is white.