Just a quick question, have anyone here ever seen a 4’ silver arowana? Not in a pond or public aquarium but in a fish tank? Or better yet has anyone ever seen or grew a 4’ silver aro in a 240g tank?
Agreed: I would wager it's very difficult to find a 4' silver arowana in any private tank, let alone a 240g -- because they mostly die and/or are so stressed they jump out of the tank
long before reaching 4' -- the smaller, more cramped the tank, the more likely an aro is to jump out.
A 240g should be fine for a year or two (if not overstocked with other fish), but it will be way too small long-term if OP wants to see the best in his fish.
I've had a lot of big dogs in my life -- even though they were 4-6 ft. long sure they would fit in 3 foot wide cages all day curled up if anyone was cruel enough to keep them in such -- I personally wouldn't. Yes my fish are in glass boxes instead of lakes/rivers, but the least I can do is give them some reasonable space to move around -- it's not just a physical thing, there are mental considerations.