Well, yes and no. The male papillae is not as large. And, it's not uncommon to see more than one showing. I have a group of angels and sometimes, several females will show to only one male, or visa versa. You just have to watch to see who pairs up. They will go off on their own, then you remove them. The papillae shows when they are ready to spawn so yeah, it's not always visible. But, it is visible for days before spawning takes place so, it gives you time to see who is together and to get them moved. Two will pair off and you may start to see some cleaning of an egg laying sight. Mine laid on plant leaves. I honestly can't say if you throw just any male in with a female if they will accept each other or not. I let mine pair up by themselves. I don't know if it can be forced. I imagine if you move two that you know are male and female, they eventually will pair up, but I don't know that as fact. I can only tell you what my experience has been.