Eh, Arapaimas require dedication and funds most people cannot afford. Hell, just feeding one adult requires more food than to feed yourself. xD
My life goal (Yep, my life goal is about fishes too!) is to have my own house built, with my natural pool (Pool filtered by mecahnical filtration and plants, designed for humans initially), and an arapaima. If I can get a bigger pool and have 2 or 10 of them, I will, but I'm not kidding myself, a single of them would make me feel complete.
If I eventually make my dream come true, and have the house and the pool, I am definitely growing it in a tank, though. I want to spend the first year looking at it from the side, before looking at him from the top for the next 20 years.