"Iain Miller" wrote

AIUI fish release a hormone that in high concentrations stops them
growing.
Therefore if you change lots of water you get rid of it from the water -
if
you don't then it builds up over time and slows their growth. Big fish in
a
small tank will release more of it hence why they might be observed to
only
be growing to their environment.


True, to a certain extent.

But that's not a good reason to crowd fish into a tank too small, or ignore
water quality either.

Would you be happy living in a bathroom that nobody ever cleaned ? You may
survive it, but that doesn't mean it's a great idea....

Limnophile