Thats the only tried method to identify male and female. There is a lot more out there, like the females belly will rest on the substrate where a males won't if they pectorial fins are down. Males have a tendency to have a higher more pointed drosal fin that females. The females pectoral fins are cupped so they can hold the egg where the males is is almost a reverse cup.
That all being said, it comes down to realy getting to know them. I know it sounds like one of those "expert" things but I can tell just belooking at them now without going into all the body details and I don;t make a point to study them. All it took was one breeding session and I can now fairly accurately tell the sex of any of the species I have kept even before mature.