I kept them successfully in higher pH/hardness but they got large water changes to keep the water really clean. They grew well and seemed healthy but you likely won't see spawning unless you give them softer water.
They can be really hard on each other. When I kept them, I gave them a large tank footprint and plenty of caves, flowerpots, and things like fake plants and driftwood. I've noticed in the two groups that I kept that each individual fish will stake out their own plant or cave, and sit idly in that spot unless they're out eating or fighting. If they didn't have territories to claim as their own they'd probably be a lot harder on each other.
I've never had them become extremely intolerant but that could also be because I wasn't spawning them.
It should also be noted that not every variant/catch location gets the nice red color that you see in example photos online. Mine were always mostly just black and white with nice iridescence on them. I'd imagine the red color may also fade on wild imports, much like the blue fades on heckel discus... it's probably a combination of water parameters and diet that keep them that color.
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