honestly i cant tell the diff as well, its much easier to distinguish when they are juvies with the present of black stripes along the fins. but hard to tell when the fish is on adult size. When I bought it was 40cm, and now is over 65cm. About the head shape, I had a silver before with similar size with much wider head shape compare to this one which is more slender. There is no DE on the fish which made me chosed this fish.