He is a DOUBLE TAIL!
You can tell by his Dorsal
DTs have a bigger Dorsal (back fin) than any other, it almost mirrors the belly fin. They are the only variety you see that Dorsal with... They come in all tail types, but the DT is what he has to be with that Dorsal of his
HM would have a normal Dorsal with a tail (Caudal fin) that spreads to a perfect 180 degrees (basically straight up and down from top to bottom) with multiple fin branches... And usually a straigh fin edge
(the male in the photo has little points to his edges, so he is either a "comb tail" or "fringe tail" ...and I am my exactly clear on the difference between those)