i have a silver arowana hes about 2 foot and a bit long now and lives in a 7x2x2 foot tank.i think anything smaller then this would be cruel as they love doing laps of their tank and as they get bigger they need a rather wide tank for them to turn in.
when i comes to food u dont want your arowana to be come dependent on live food as it will stop eating anything but live food and that costs alot if ur having to buy feeders(also feeders are normal poor quality can can have who knows what wrong with them)
you should be able to buy floating sticks specialy made for fish like arowanas or chiclid pellets might do the trick.also get some frozen shrimp from the supermarket and feed them to the arowana(make sure not fozen) if they sink dont worrie the fish will soon learn to go get them off the bottem,also frozen mussles work well just chop off the grissely bits and chop up small enough for the fish to swollow.
with feeding such high fat foods u need to keep the tank clean and do regular water changes but u probaly allready know this.we find running 2 canerster filters and doing a 20% water change each week works realy well and we have a pleco that help put up all the scrpas so they dont rot...after feeding it helps to take out any food the arowana does not eat so then its lass work for later ok.
hope that helps a bit..also it will eat anything it can fit in its mouth and it has a huge mouth
pm if u need any more first hand help