Any new pics of your tank?
BTW I added a Dorado to my 15k last year. It was a real eyeopener. He was about 15" and once adjusted to the tank just cleaned out dozens of cichlids 5" or smaller. Friends visiting have been riveted to him in his never stopping search to eat whatever he can. He eats pellets and thawed mackerel, smelt and herring also in huge amounts. You are right on about the gold colour too. Mine is still silver bodied and about 17" now. However in natural sunlight (Window faces into the tank on one side) a glimmer of gold is starting to show.
My Boulengerchromis is the only fish in the tank that will turn on him and put him in his place at present.