I understand where you're coming from with your theory, I just am having trouble with a couple of points. If golden trout were to become more agressive and predator resistant due to their color, I would think it would take many generations of fish in the wild becoming that way due to the most adapted fish being successful. That type of natural selection doesn't have a chance to take place in a controled hatchery environment. I also am not sure that a trout has the ability to think to itself, once released into a pond or stream, "Hey, I'm yellow I better go super crazy for food and be really careful that nothing sees me so I don't get eaten." I suppose that the fish that have that disposition naturally may survive longer than ones that don't, though.
As far as there being a "true" golden trout, I still maintain that it is possible through line breeding. It may vary from hatchery to hatchery as to how far away from the rainbow a golden has been bred. The less intensive the line breeding, the higher chance of a regular rainbow being spawned, and some hatcheries may prefer it that way to keep the goldens more genetically diverse. My line of thinking is that you don't see German Shepherds having Collie puppies, so I would think you could produce golden trout that only have golden trout offspring.
This is the Jack Dempsey I was talking about, which isn't a hybrid. There is a reference to the electric blue one I brought up, as well:
http://en.wikipedia.org/wiki/Jack_Dempsey_(fish)
It's from Wikipedia, where anyone in the world can write anything they want about any subject. So you know you are getting the best possible information.
