most foods use colour enhancing products tbh. maybe set up an experiment topic about it then....I am going to do an experiment and stop using it for a while. Could well be the colour enhancing ingredients. Maybe they are like E numbers lol.
are your fish aggressive then?
I would say more grumpy than agressive. They have all picked their own parts of the tank where they relax, but sometimes when they meet in the middle they have the occasional push at each other.
The only agressive Cichlid that I have ever owned was my Ellioti, who used to swim around the tank hunting my Severum down. He also killed a Blue Acara through bullying when they were both juvinile. Might just be a coincidence, but he used to love eating Hikari Gold.