This hybrid section has grew recently and noticed that lots of people are asking for "proper" care info, so I thought this would be helpful to the new FH keepers.
Flowerhorns are no special than other cichlids, however, to bring out their best in them there are couple of things, you have to consider couple of things.
1. BACKGROUND: It CAN NOT be black! This is rule number 1. Even if you have a $1000 fish, if you have black background, they will turn gray,black,head goes down,redness will be washed away and etc...... No, they will not adjust over time. FHs love colorful environment. If you can't stand other color backgrounds other than black, well FHs aren't for you

Any colorful backgrounds are fine including solid blue and plant backgrounds!(now that's a relief isn't it?

) Even NO background is better than having black background!
Now, there is an EXCEPTION. Any fully faded flowerhorn will actually like, or at least don't mind this dark black environment.(SRT, Jing Kang, Parrot etc...)
2. GRAVEL: You guessed it!

Can't be black! Has to be colorful. Now..... most of us(including myself) can't stand bright pink,green, and purple color gravels

. Just natural gravel is bright enough and will do the trick

No gravel is fine as well, however I do recommend to have a background if you aren't going to put gravel in the tank. When there's neither of background and gravel, they seem to turn pale and show stress bars(when they are fairly new to your environment)
JP