I had a TSN once in my younger days. I knew better, but purchased it in a moment of weakness. Cool fish, but grew really fast, was expensive to feed, and got rid of it after only 10 months because I knew it was going to have problems housing a fish that should grow 36"-40".
I wouldn't keep any fish anymore in a tank that has the potential to grow more than the width of the tank and feel the tank should be at least twice as long as it the minimum width to allow for swimming room.
As a better alternative, if I were to take that route again, the lima shovel nose is much more fitting for being kept in the home aquarium.
I also had a silver arowana once upon a time. They are very, very skittish IME and you had to be sure it saw you coming so it wouldn't freak out. Mine was around the 20" mark when once night it just decided to jump for no good reason. I had heavy glass lids on the tank, so it hit the lid and broke it's back. It couldn't swim. If people think it's hard to euthanize hybrid fry, try doing it to a large,m personable fish that you've kept for a number of years. I wouldn't keep one again in a tank with a lid. Instead use a mesh enclosure around the top so it has some give in the event the fish jumps hard.
In the end, I also think it's cooler to have friends with MONSTER fish than it is to keep them yourself. They are fun to see from time to time, but don't do a lot (watchability over time isn't as good as a tank full of small, active fish), require a huge tank, and cost a lot to feed.
