You are going in the right direction.
Good quality, varied diet. Better living environment. Keeping a good number of social fish together.
Yes, fish colouration will wash out when the lights go off. It returns pretty quickly when the lights come back on. 12 hours a day is a bit much though. This will promote algae growth and green water. 8 hours a day is plenty, or go 4 hours on, 4 off, 4 back on.
And remember that those online photos are fish at their absolute best and photos can be enhanced too.