I have recently purchased a 12cm sivler arowana. I am feeding it roughly 8 hikari arowana foodsticks a day. Is this enough or should i increase this or maybe add some different foods in?
Usually with young fish, I aim for more than once a day feeding to avoid stunting. You certainly can feed several times a day but you must make sure when you feed that the amount of food is not too much that the arowana ends up looking rather bloated which should be avoided as it may cause health issues in the long run. A fish has its limits and it is up to us to control that.
Varying the diet is the key. Sticking to one particular food only will not enable the fish to absorb and utilize different vitamins needed to ensure proper body growth and development. Aside from commercial foods, you have the option to try small shrimps, mosquito larva, bloodworms and many more.
Agree with Lupin. Mine is a bit larger (~15") and I've pretty well settled in to twice a day with the staples being hikari carnivore and f/d krill. Another good option for variety is insects, like feeder crickets and the like. They're a natural food source for aros and pretty nutritious. But yes watch the gorging, particularly when feeding "treat" type foods like insects, shrimp, or krill.
My black arowana is about 15" and I feed him massivore, cichlid gold and freeze-dried krill. He loves the cichlid gold the most, looks like a giant pacman when he eats it, Haha!
I feed him twice a day usually, but he doesn't always eat the second time around. I have enough other fish in the tank to eat the food though so it isn't wasted.
I feed him market shrimp (dehorned) sometimes also. He doesn't always eat it though, as he doesn't really grab stuff from my substrate and it sinks pretty quickly.