Tbh if you have a tank large enough to house them in future then a small tank is a great idea to help grow them.
But not having a plan to upgrade is no good. Saying you have a tank that is too small and not meeting the rrequirements is useless. Keeping the fish in a small growout tank is PATHETIC and animal cruelty, especially if you just dont care!
I would say only buy fish that grow large, IE Oscars if you have a setup or money set aside to house the fish long term.
If someone has a multitude of problematic events like
pacu mom
then I understand as long as the fish gets into a large home as soon as you can get it going.
I was tempted to buy an oscar for my 68Gal, but I thought it would be cruel to keep a wasteful fish in more than 30 gals less than it should be because I am busy and cant do multiple large WC a week.
Thank god in south africa we dont have chain stores (walmart etc) that are promoting animal cruelty. The fish shops are few but they know what their doing and hold oscars and only stock tank busters on order to prevent these issues.
Rant over and thats just my 2c