You are going to get alot of negative feedback here about that. You'll soon find out why.
I'll simply say this. Picture the Great barrier reef, billions of gallons of water. Fish swimming freely everywhere. Now picture even a monster tank (500g) sitting on the bottom of the reef, a spec in comparison. Is this really enough room for any fish? No, not really but we do it anyway. I've seen extremely overstocked big tanks, 30+ big fish in a 180 where half the swimming room is taken up by rocks and corals but no one bats an eye. It seams once you go north of 150g people just look the other way and forget the whole size rule. I've seen some species of fish (12in+) on here and elsewhere in 120-150g tanks that clearly need public aquarium size tanks and not a single bad comment, only ohhhhhs and ahhhhhs.
So take what you read with a grain of salt and always practice responsible fish keeping etiquette. Some fish may outgrow your tank and recognizing this months before they do is essential, don't wait until it actually outgrows it, Or is showing sings of stress because of the lack of room. Educate yourself in fish behavior so you may better identify the sings. Or don't I'm a comment not a cop.