Sweet it should grow very quick as mine has. what size tank is he/she in? What are the tank mates?
Flowerhorns don't usually do very well in community tanks as they get very aggressive as they grow. My thai silk flowerhorn is 5 inches in length now and has killed a 6 inch jack Dempsey and a 7 inch buttikoferi. He's now in the tank alone as he's just too aggressive
The fish you have will be ok in a 75 gal apart from the bass. They need around 125 gal+. Don't be surprised if the flowerhorn takes over the tank and starts to kill tank mates as it grows. Mine was no threat what so ever until he got to a little over 3 inches and then his attitude changed almost instantly. Not saying it will definitely happen with yours but iv owned alot of cichlids like oscars, severums, firemouths, jewels, red devil, red terror, jaguars, jack dempseys and buttikoferi and the flowerhorn is by far the most aggressive even though he's still only 5 inches. The only cichlid iv had that was more aggressive was a dovii/wolf cichlid.
Flowerhorns need a minimum of 55 gallons to themselves but a 75 is obviously better. Mines alone in a 125 gal and like I said I can't add anything with him.
I got 2 videos of my thai silk on YouTube... Feel free to take a look.. My username is dbanner2804... Mine was an impulse buy too but now I'm so happy I got him... Even if it means having a big tank with only 1 fish he looks fab IMO and has so much personality. He eats from my hands and does funny loops to get my attention
Glad to hear he has settled in. When the flowerhorn gets comfortable in the tank he will likely bully everything in the tank... But... The peacock bass will get to around 2-1/2 feet in length if in big enough tanks (like 300 gallons or more) and they have very big mouths so the bass could possibly eat the flowerhorn without too much effort. Having said that your bass will get nowhere near that size in a tank the size of yours. It is more likely to get stunted because it hasn't got the room to grow. This means it will stop growing on the outside but it's internal organs will continue to grow leading to an early an unpleasant death.
So taking this into account I'd be a lot more concerned of the flowerhorn killing everything else at some point, its not a nice thing to see. They are very aggressive once they mature at around 5-6 inches and they are very terratorial.
Like I said though, nice to see he/she has settled in