The debatable topic aside (which I'm not going to get into again, it's pretty much a trench war), remember that when you get right down to it fish breed for one of two reasons.

1. Conditions are optimal for the offspring. Food and high water in abundance are to be expected.
2. Conditions are likely to get really bad real soon. Some scattered eggs may be the only way for the species to survive. That's something you see in annual killi for example.

I suspect that if you real dive into this you will find that the first factor comes into it. But perhaps you'd better take this to the cichlid subforum or even a dedicated board.