"Jon Pike" wrote in message
. 159...
I'm sure you've all heard this idea before, that fish of various kinds
will
grow to fit their environment, and then stop growing.

Does anyone have good -reliable- information on the matter? I'm sure
everyone has opinions, and links to opinions, but I'd like to get a handle
on some facts if it were at all possible.
TIA username=moosespet

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.

I.