Thank you so much for all of the wonderful advice. You are so generous to give so much detail.
I suspect that my Brazilians probably are not getting as much carotenes as they get in nature, so I will work on seeing that they get a bit more of this through more frequent food enrichment with vibrance. And I will see if I can get some more bright orange/red hitching posts for them (though they do tend to have their favorite spots which are often not the most colorful perches in the tank).
Many thanks again,