To cook fish in foil on the grill takes around 12 to 14 minutes.
Melt some butter in a saucepan and then pour the butter onto the fish and add some salt and pepper, lemon juice or parsley if you'd like for the taste.
Then wrap the fish lightly in foil and leave room for the fish to expand in the foil.
Cook one side for 6 to 7 minutes and then flip the fish over and cook the other side of the fish while it's still in the foil.
After 12 to 14 minutes the fish should be fully cooked.