Are some fish okay with a higher pH if the hardness is correct for them?

[Byron]

Problems with the water? Or did you mean with the tank and/or tank mates?
When you say "and the tetras", is that about whichever problem would apply to the congos too?
Thank you

Sorry, I was only pointing out issues between the fish species.

 

[rebe]

Sorry, I was only pointing out issues between the fish species.

Thank you for clarifying