Definitely overstocked long term, ~190cm of adult fish in ~240l of water, at least two of those larger social mid/upper water groups should be moved to another tank.
I hope you are doing substantial (>50%) weekly water changes, because even as youngsters if you are are feeding these fish enough to grow to their potential adult sizes (2-3x per day), their tank water will be very different chemically to "fresh" tap water (don't just think ammonia/nitrite/nitrate). Even with extra large water changes (3x ~50% weekly), my ~50 Steatocranus youngsters born a year ago were nothing like the size of the 13 youngsters from the previous years batch after 8. months