BenSow, I don't want to hurt your feelings, but i think you made a bad choice in buying a sliver. I know you are aware it's going to get too big for your 55 gal and you'll need to get rid of it, but i have a suggestion Id like you to think about.
Considering you're already having problems with the silver because you can persuade your Mum to buy the food you want it to eat and the fact you know the tank is going to get too small very soon. Why don't you think about taking the fish back and getting something that can live for many years in your 55 gal.
You're going to get attached to your fish and when the time comes you might be sad to see it go, you may even grow it big enough that it becomes hard to get rid of, meaning you end up keeping it in a small tank longer than you anticipated and you start to beat yourself up over it. You could end up unintentionally hurting your prize aro! People are often put off by the size of silvers once they start to get biggish.
There are plenty of fish that can live in your 55 for a long time, all through your school and if you treat them right all through your collage. If you can imagine how it would be to beat yourself up over the wrong choice of fish because of the negative things that could happen as a result of owning it, imagine how it would be if you own a fish healthily for the next 5 or 6 years.
Even better, imaging in 5 or 6 years when you're working and you still have the passion for an Arowan but you have the money to buy you own monster tank and feed the fish whatever you please, why, you live in KL, in 5 or 6 you'll be buying a set up with an Asian Arowana in it.
Seriously BenSow, give it some thought, is now really the right time for you and an arowan?
I sure you can still post here if you want to, and Im pretty sure everyone will support you in becoming knowledgeable about aros, Asian or silvers. Honestly I respect your enthusiasm in buying own and you have great taste because you love the best fresh water aquarium fish there are, but youre just not set up for owning one yet. Please give it some thought.
I don't know much about different species of fish but Im sure some of the other posters can throw a few ideas in.