Lamprologus Caudopunctatus

On Sunday I purchased 6 Lamprologus Caudopunctatus and according to our LFS I have 3m & 3f.

I need some advice about the breeding habits.

Very beautiful species. They need a 35-40 gallon tank with fine sand on the bottom and they like to breed in narrow caves. The funny thing is that I read about this species yesterday on another forum.

They are currently in my 210gallon community tanganyikan tank. Tonight I have noticed that the group had gathered near the leleupis cave,trying to enter cave but leleupi had chased them off. I do have plenty of rocks with caves hoping that they use to setup a breeding area.

2 caudopunctatus had just disappeared from my tank, I think they might have been eaten by my frontosas during the night. I sold off my 4 frontosas to a friend.

How does one determine the sex of these fish, over then weekend I had observed 2 tackling each other which I would think might be males. Their gills expanded and fins all streched out. The other 2 does not bother with each other just busy rooming around my big tank