With hybrids, the black dorsal spot isn't 100% accurate. While it is true that in ZZ's, if it has a dorsal spot, it will most likely be female, but theres other things you gotta look at in sexing. Body shape, facial structure etc.
Humpy head, lol, thats funny I dont get into all that kinda stuff...just make sure clean water and that he's the boss...also additives cant do too much for genetics.