I just got a breeding colony of demasoni cichlids in a 150 gallon. About 12 of them between 1.5 and 2.5 inches. In there for a month and still not breeding. Is this normal? Some info if needed: --> substrate sand with lots of holey rock. Parameters are mint, no high nitrate,nitrite or ammonia and a ph of 8. Feeding them spirulina flakes which they love. Any advice?