WOW~~ as I said in another post about him.... Lucky you! He is stunning.
I also have problems taking pics of my fish with the flash....it makes my blue fish look greener, and my yellow fish look blindingly flourescent. I have tried to overcome the problem by taking pics of my fish in the window of time between 7am and 8am when the rising sun shines into the room at such an angle that shows their true colors and gives enough light where a flash is unnescessary. Try experimenting with taking pics at different times of the day and also taking whatever lamps you have around the house and position them over and around the tank. See if that helps.