I think it might get sick of the small food as it get bigger, I can't imagine a 2' aro eating colourbits. But its good that its taking prepared food, and you should persevere with other pellets.
That TetraMin color bits does not harm your aro but it also does nothing to enchance your fish colors. I used to feed my angels and discus this stuffs thinking it would help but nothing like advertised. HaiFeng pellets is good stuffs and flowerhorn enthusiasts love it. If you have access to Sumo then it's worth giving a try. I feed my guy HaiFeng pellets and Hikari krills. So far it's working great.
If your aro isn't eating commercial pellets/sticks, I believe this is certainly a way to gradually introduce them to his diet seeing as how the flakes are commercial food.
u can try freeze dried krill. its a natural color enhancer. most aros will take it immediately. shrimp has saturated fat so krill is a good substitute. feed it whichever its your decision.