They are one of those fish that's caught wild instead of raised in captivity. They can be sensitive so therefore harder to induce breeding behavior, may not be what you want to hear but it's a fact. As long as you have a tank to sustain a good school (algae), keep some in super good condition maybe you'll be able to have yours breed.
Imho corycats are much easier to breed and fun to watch, hopefully mine breed again soon[emoji4]