Butterfish are aptly named; they're smooth and buttery with fine flaky white flesh and have very little fat. They're easy to eat whole, since they have relatively few bones. If you can't find butterfish, use pompano or mackerel.
Prepare a stove-top griddle or outdoor grill with the rack set 1 inch above the coals. Allow the grill to get very hot.
Meanwhile, brush the butterfish with the olive oil and season with salt and pepper. Grill the butterfish about 3 minutes per side, until the fish just begins to flake. Arrange 2 butterfish on each of 4 dinner plates, garnish with the parsley, and serve.