George I am just telling you what I expereinced. Mine bred and I raised fry from two of the species he mentioned in HARD 8.0 WATER
In actuality some rainbows ... most rainbows come from hard water.
Here is an article on one of his species.... it's says 8.0 water :
http://www.aquaticcommunity.com/rainbowfish/boesemans.php
There is a common misconception that all rainbows come from the same PH. It just isn't the case. That is why I asked him which ones.
I've seen the habitat some rainbows come from.... with all the mineral content it has to be hard.
I believe the "blue neon" ones are soft water... which are probably the most common rainbow. But I'm not 100% on that as I have never kept them. It would explain the misconception.
You can put rainbows in almost any water and they will do GREAT and spawn ! But if you want to be "true" to where they come from.... they come from hard water
I also kept some species in "softer" ( around 7.2 ) water with cories. Both still spawned and did great.
The only issue is aggression... but the tangs he is putting them in with are not fast enough to beat up a rainbow. Rainbows are freak'n FAST FAST FAST.
Best dithers for tangs.... danios and rainbows
