I believe you can sex them by the dorsal fin. I had my choice of a male or female when i got mine and you could see the distinct difference. But other than that i have no idea.
I have my hands full with just one mandarin LOL Can't imagine having two to worry about
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.