The first thing you need to understand is that you are not in total control. If Discus do not want to pair off, there is nothing you can do about it. The only thing you can do is provide the right conditions so that it is more likely that they will pair off.
If you have a sexed pair and they are the only discus in the tank, it is likely, about a 70% chance, that they will eventually pair off if left together for a long period of time.
To hurry our potential young lovers along, we provide conditions that are conducive for fishy love. We put seven mature Discus in a 125 gallon tank and let them acclimate to it for two weeks. We then start doing some sudden changes in the tank conditions to stimulate courtship. Some of the changes we make are
- Change the water temperature to 78 degrees for a few days and then bring it up to 88 degrees over about 12 hours and then leave it at 88 degrees for the remainder of a week.
- Let the tank get somewhat dirty, not doing the daily water changes for a few days and then doing a 80% water change.
- Feed them heavily for a few days and then stop feeding them for two days, followed by feeding them live food for three days.
- Do two 60% water changes four hours apart where the Ph goes from 6.5 to 7.0 at the first change and then from 7.0 to 7.5 at the second change.
- Leave the tank dark for two full days and then turn the lights on for two full days.
If we have tried all of the above and after two months they still have not paired off, we switch out four of those discus and start the process over again with four new discus along with three remaining.