I've been feeding Nori on a clip and mine love it. It's real messy so if you choose to try it keep a turkey baster handy. I also feed some NLS Algae pellets.
It's a gorgeous fish.
I'm going for more competition looks so my feeding regiment is changing up some and less of the nori and algae will be fed in the future.
nori and algae will color up the blue, green, and yellow on a flowerhorn. The best is spirulina.