Starving is cruel. There is a much better and quicker way to get fish eating what you want them to eat. It nearly always works.
Feed the fish as much as it can eat of what IT WANTS TO EAT. Keep it as full as possible, as it's stomach stretches to hold more and more food. Once it's stomach has stretched to a large size, it will feel hungry when it has digested a small proportion of its stomach contents. By the time it has digested half of the contents, it will feel VERY hungry and will be willing to 'top up' on other foods.
Example..........you've starved your Aro so its stomach has shrunk, and you could probably fill it up today with just a few worms. Let's say 2 worms.
Feed it as many worms as it wants for the next week, and its stomach will expand to hold maybe 10 worms, say. Stomachs send a signal to the brain when they're full. They also send the signal that makes us feel hungry when they are not full. A person who eats big meals will feel very hungry when his stomach is only partly full, even though he might have more in his stomach than someone who only eats small meals and feels full.
So the more you feed a fish, the hungrier it gets between 'meals'. Its not cos they get gready, its because they really are hungry, cos there's room in their stomach for more food. Your Aro will get hungrier and hungrier between meals, and will try (and accept) anything you offer it. It will be constantly hungry as it will have a big stomach to fill. (Starving shrinks the stomach, so the fish will never feel all that hungry). Then you simply start to offer more of what YOU want, and less of what IT wants.
I hope I've explained it well enough. THIS METHOD WORKS much better than starving, which is the cruel way to do it, and doesnt always work.