1, the mouth shape is different: the mouth of the island fish is relatively normal, and the side view is slightly inclined; The fish's mouth is upturned, and the gap between the mouth and the body is almost vertical.

2. The color of the fish is different: the back of the island fish is slightly blue-gray, the sides are silvery white, and the fins are gray-black; The fish's back is gray-black, and there are often 1 gold glands in the scales at the lower part of the body.