The african arowana, Heterotis niloticus, is extremely time-consuming to keep alive as juvies in aquaria. They basically have to have access to food constantly until they reach about 8" and their bodies start holding reserve fat. These are filter feeding fish that can reach 3ft in length. I raised them on dense culture crumbles, frozen bloodworms, mysis shrimp, brine shrmp plus, cyclop-eeze, mosquito larvae, and daphnia. Leftover foods made up the "constant" part of their feeding regimen.
I kept mine going by keeping them in bare tanks with sponge filters. The sponge filters were beneficial in that they attracted food to their surface which the aros grazed on between feedings. Water chemistry is hard and alkaline with rift lake salts added to the tank. Water changes are every other day and sponge filters each are rinsed off on alternating days to keep spoiled food off the aros grazing areas. The tank receives direct sunlight to 1 side for an hour or 2 a day. The water is pretty green (to match their native waters).
Young can be kept together for only a short time, as very small fry, before they become intolerant of each other and begin fighting. The stronger one will harass the smaller ones until there is only one aro left in the tank. As sub-adults, they become tolerant of conspecifics again. I have other small growout species in with my young aros and they've never bothered them. These fish are active in all areas of the tank and are always on the move.
This is an awesome species if you can resolve yourself to being extremely busy on their maintenance for the first 6-8 months or so.