In my experience cory`s breeding triggerers are 3
1.The water level.
Keep the water level 3-4 inches lower than usual for 5-6 days.
Then fill the tank with any water.
2.Do a water change of 1/3d with colder water
In summer do a 2/3d water change . These changes must be repeated after 2 days.
3.Place the pair fish in a new tank.
If nothing happeds check some details.
-Are they at least 1 inch?
-To sex correctly:
The female is rounder, usually larger in all dimentions.
Male has a thinner body and looks somekind more delicated.
Male if matured presents somekind of a reddishing on sides like blood under the skin,or maby
like the face of a shy child.It is slide but observable.
(look carefully and you will see it).
To see the female running and sucking the wall glasses is a good sign.
To see the male chase the female across the tank it is also a good sign.
To see the female pushing the males belly in the "T" shape , it is a matter of seconds to see eggs on the
glass or on plants or everywhere (preferably on points where water current is stronger).
After 24 hours remove the parents and any other fish.
It is best to have the parents in a nursery tank and remove them after 24 hours after laying and spawing
leaving the eggs alone. (parents possibly eat the eggs and fry ).
Do dayly water changes with colder water .
After 4 or 5 days all fry will come out of the eggs and swim nervously left and right.
Give them shelter.
Bio-fiber green works well.Any shading material works, otherwise the fry will try to enter the sponge filter
and many of them will be lost.
Start feeding at day 3. Thin flakes to dust with your fingers.No need for baby fishfood...