1, the mouth is different: the parrotfish's mouth is similar to a parrot's beak, very large and the upper and lower jaws can be active, can easily bite open hard objects. The mouth of the bluegill is smaller and the upper and lower jaws are not movable.

2, the use of different: parrotfish is usually used as an ornamental fish, people are kept in the aquarium, to appreciate its beautiful appearance and unique mouth shape. Whereas, the mackerel is usually used for food, which can be used for soup, pickling, cooking and so on.