Someone needed to add to your recommendations so they don't stand alone.
I am trying to approach the captive breeding of Heckels by growing my potential breeders in just my tapwater.
If a pair forms then I will give them their own tank and gradually change the water to approximate their natural habitat during their spawning season.
Others, like tratore, are following the best advice to keep their Heckels in more natural water conditions at all times.
These are just some of the experimentation that needs to be done to sort out what the key factors are for getting our Heckels to spawn and raise healthy young.
Eventually we will understand them better. Something tells me Heckels have to be easier to "domesticate" than many of the reef fish now being bred commercially.
Larry