If they are anything like Pompano they should be really good eating. The ones at shoppers were only about 6-7 inches long.
The Pacific pompano and the harvestfish are close relatives to butterfish
Atlantic butterfish are plentiful during the late spring and late fall; Pacific pompano are available during spring and summer.
The secret to successful butterfish cookery is do not overcook. Whichever of the following cooking methods you choose, your butterfish will be cooked when its flesh becomes opaque but is still moist, and can easily be pierced with a fork. For grilling and frying, leave scales on but cut off the head and tail with a sharp knife. For baking and poaching, rub off the small scales with your fingers.
Baking
Place butterfish in a greased baking dish or wrap in oiled foil and place on a baking sheet. Brush with melted butter or oil and season with salt and pepper, or cover with a piquant sauce. Bake in a preheated 450°F (230°C) oven until done, about 10 minutes for each inch (2.5cm) of thickness.
Grilling
Place the whole small fish directly on greased grill, 4 to 6 inches (10 to 15cm) above prepared coals or fire. Baste with butter, oil, or marinade, and close hood of grill. Cook until fish is opaque and moist on the inside, 6 to 8 minutes.
Pan frying
Coat butterfish with seasoned flour, crumbs, or cornmeal. Shake off extra coating and fry fish in a small amount of hot butter or oil, turning once halfway through cooking time. Cook until opaque and moist on the inside, 4 to 8 minutes.