First off, they are temperate water fish not tropicals.
They do best in the upper 60's F.
The are from Europe and Asia.
The best bet in breeding them is to get them in a tank with a lot of leaf litter and no other fish.
Let the tank drop to room temperature and slowly raise it to about 72F.
When a large pressure front is about to come thru, do a 50 %
water change.
This should trigger the fish into spawning.
Once they have spawned, move the adults out of the tank, so they do not eat the eggs or fry.
Good luck.