Well put, Oddball and Kiril. Once one learns the basics, no fish of that keeper has to outgrow any enclosure.
Aronus, welcome to MFK! RTC is one of the most well known and written about and studied large cats in the trade. If you don't trust forums thinking people just re-tell stories, you certainly should trust datasheets / profiles from such highly reputable sites as Planet Catfish, ScotCat, SeriouslyFish, Aquatic Community, etc. etc. etc.
Fish don't grow to the size of tank. One can make them, more or less, sure, but that's not fish keeping, that's considered animal cruelty by those who understand and always results in a stressed, deformed, stunted, sick, and most usually soon-to-be-dead fish.
Yes, I've had a privilege of keeping more than a dozen of rescued sub-adults RTCs. In a 4000 gal indoor pond.