I have a male (about 8", still hasn't put on a lot of bulk, more RD'ish) and a female (about 6", quite stocky, more Midas'ish) in a 50gal breeder (36"X18").
They were in there to grow out and see which one I wanted to keep. They were divided by an egg crate divider. After some time, the female laid a couple sets of eggs, which of course were not fertilized.
I then found them on a couple of occasions together because they knocked the divider down. It happened more and more fequently, until I just took it out. They have now formed quite a strong pair, but have not spawned yet. Just a bit of jaw locking, but not even a split fin.
I would divide the tank, get what you think is a male of similar size, and leave them like that for a while. Then remove the divider and watch them like a hawk for severe aggression.
All fish are different, you have to find one that is compatible...
Good luck!
Burt
