Very killer looking fish either way! I think there could be a couple of different factors. One I think lighting from one tank to another can make a fish's appearance change. Secondly, what do you feed? Different foods help bring out the vibrant colors. A good variety of foods can help enrich ones fish's colors. Flake, Frozen, etc.... Hope to help. I am by no means positive on this causing the fish to change colors so I hope others chime in as well.
Eric