That's true, but I'd have to increase the size of the tank as he grew. And I like to just start with the right tank size to begin with, so easy lol! It's like my latest pup, husky/malamute mix, started in a little $45 kennel, now he is up to a $160 kennel and who knows if he will outgrow that. Pricey to keep upgrading.
If they would be satisfied in 40 gallons, I'd go for it, but with how big they get...eh.
I'd like a oscar, although personally I'd be sure to get the right size tank first off- I don't like keeping fish in small quarters, but that's just me. Nice fish! Like Newman said, bigger is better.
At the lfs (before they moved- now the guy who own it is testing them in an outdoors pond) they had a 450g pond with oscars, headstanders and red devils, not to mention the aquascaping! I'd love to do something like THAT one day.