Here is a copy-n-paste on what I posted on the other forum.
OK...so for how I used to get these to breed.....simulate their seasonal changes.
In this batch I bought 4:3 males:females, but that is to give me a 1:3 male:female ratio in the end.
3 of the males will be removed when one shows his dominance.
The water is kept in good condition (with a low conductivity, peaty, and soft) for a long period with very regular partial water changes, then there will be a period of letting the tank 'slip' a little:
water changes will be reduced, pH will rise slightly, conductivity will rise slightly, and the lid of the tank will be removed (making sure the fish can't leap out). Feeding will be reduced somewhat, and the filter speed will be turned down.
Have bogwood etc that will be ultimately out of the water and thus effectively reducing the width of the water as the water level lowers....simulates narrowing stream banks.
Now, this is slightly dangerous for a delicate fish such as these....so it needs to be done with care.
Having modern zeolite resins around (such as ammonia absorbing clays or JBLNitraEX is a good idea).
Then, do a largish water change......add in fresh water, and slowly reduce the pH and conductivity, add more peat and ammonia adsorbing clays (this will also increase the 'mulm' on the bottom of the tank....that is what you want).
Increase the flow of the filters, and have some water trickling in from above.
Add the lid, and increase the air pressure. Feed plenty of frozen food (bloodworm).
.....and keep the fingers crossed. These are not always a 100% guarantee to breed.
Now, they sometimes may spawn on the odd occasion in the tank anyway, but that is leaving things to chance a bit too much.