mine were in a well planted 4ft tank, for a few months, and nothing happened. i moved them yesterday into a 3ft planted tank which had a 95% water change (left enough for the fish to swim in). it currently has:
+/- 150 bristlenose babies and dad
about 50 white cloud mountain minnows
a breeding pair of siamese fighters
and the 10 cories.
from there they did it on their own
as for sexing, the females are bigger than the males. thats all i know.
from that i have worked out i have 5 females and 4 males. i'm still unsure what the last is.
from what i've been told, it pays to have more boys than girls.