Charlie, you brought up an interesting theory with the light. I remember Bob not happy with his peacocks and haps when they were displayed at Scales for sale. Of course lighting has to be adequate for potential buyers to view the fish. But he always would remind me that they looked so much better back at the warehouse. And I'm sure they did.
There is no question that the more artificial light you have, the more washed out the colors will be, particularly on vivid colored fish that display inconsistent coloration due to their dominant behavior. Since male peacocks show more color when breeding and when establishing a higher level on the hierarchy, they are examples of fish that don't sustain a constant coloration. I feel that the lighting issue is a evil that is unpreventable if you want to see your fish without a flashlight in your hand all the time. Also consider the temperature of the light source. Some lights will actually make the fish look more vivid and saturated. While others will wash the color out and/or give them a yellowish tint. Often it is the personal taste of the fishkeeper on how they want to view their fish.
Bob, I have successfully raised a variety of male peacocks in the same tank for years. And normally, they all show dominant colors. A good example would be when I had two beautiful male yellows show phenomenal colors together. One a sp. stuartgranti maleri and the other a. baenschi (the one that just did well in the aquafest show). They grew up together and constantly fought, but were always quite colorful. (BTW, the baenschi was the long time survivor). The same species males on the other hand will not normally show more than one dominantly colored dude. In a big enough tank that is overpopulated, you may have a few of the same males show similar colors. But they often take turns on who is "king of the jungle".
Also would like to mention that keeping a few of the same species males together can be rewarding too. They will take turns on the heiarchy. A subdominant male may actually win a battle or two and make the more dominant fish become passive. Over a little time, the roles will reverse and the sub fish will become the dominant one. I have witnessed this several times in my own tanks. Kinda like a Rocky movie. :lol:
When keeping an all male peacock tank, be prepared to have fish with like colors to constantly fight. I added a Lemon Jake (a. jacobfreibergi 'Undu Reef') and it would be in the mix with the baenschi and the s. maleri. The ruby red would pick battles with the s. maleri too. Perhaps because the engineered lines for this fish came from the yellow sunshine peacocks of the stuartgranti strain. The a. hansbaenschi and the a. hueseri were the two blues that always went at it. Then when I introduced a flametail (a. stuartgranti 'Ngara') to the blue mix, the three of them would battle each other.
At one time I had about thirteen different male peacocks in the same 120g tank, all showed good mature coloration at the same time. And they weren't alone. More than a dozen male haps were in there too. However, I will admit that aggression ran it's course. But then again, why keep aggressive fish if you don't want them to entertain you?
I still have the tank running with six peacocks (flametail, lemon Jake, ruby red, German red, blue neon, and usisya), five haps (fryeri, gracilis, turquoise hap, mloto, and p. phenochilus), five clown loaches and two synodontis. And while the peacocks are all showing mature color, they are also showing their age and battle wounds.
While this doesn't directly deal with line breeding for color, this is my experiences with the peacocks Bob. Perhaps not scientific, but candid. :winking0011: