I use spiruina and algae based products like Algaemax, along with fresh veggies.
But I believe just as important as food, are proper temps.
I killed number of haitiensus until reading temp reports from natural habitat, water temps in the high 80s, low 90sF are not unusual for haits.
And just the opposite temps for beani, although I read posts that they are prone to bloat, this was never a problem for me for beani.
Because they are the most northerly cichlid species on the Pacific coast of Mexico, I kept them in the high 60sF to low 70sF. Nights are cool in their area, so it may be water has a diurnal variance, or just plain stays cooler, but the lower temps worked for me.
I also believe water temp has a impact on the ability of how a fish digests its food.