I've only heard rumors of a breeding colony with lots of area for each pair and lots of mud, they dig lots of burrowsThere's still the original three males and an additional one female. Finding more septemradiatus females has proven to be a bit tricky...
One of the males is actually digging a sort of a "nestpit" kind of thingy under the foliage of the Samolus, but the female seems to have no interest in him...
I dunno if there's something I can actively accomplish in order to "start a breeding colony", but I wouldn't mind if they did it on their own.