Genes, lots based on the genes...I'm pretty sure you know all about what color enhancing foods work...Krill and Hikari Bio-Gold pellets....Keep it varied....(1-2)25% water changes per week and beefing the temp up to 81-83 degrees will make him grow out more....75g and up is recommended for a single showcase...These fish are number 1 on my "owner responsive" list...Since January of this year, I've raised a 2inch male to 9inches in a 33g...Yes, the tank footprint is like most asian flowerhorn setups overseas, but I do plan on upgrading him to his own 100g soon....