In article ,
says...
I saw a post on a goldfish website from a woman whose sister-in-law was
keeping 4 common goldfish in a 1/2 gallon tank. The sister-in-law had
another 6 commons in a 5 gallon tank.

After scolding her sister-in-law, the woman purchased a 30 gallon tank
for the sister-in-law and convinced her to take some of the goldfish
back to the store.

It's going to be almost impossible to get anyone to follow a 20 gallons
per goldfish guideline.


Well, I don't think it's really necessary to try to go that far.
The point has always been that the the more water water you can
give to each fish, the easier it will be to adequately take care
of them. It certain _is_ possible to keep a gold fish in a
2 gallon bowl; it's just a lot more work to do so, and more
importantly, the margin for error is much slimmer. Miss a
scheduled water change and the fish gets hurt right away.

Most beginners aren't going to commit to daily water changes,
so it's best to give them a realistic 10G/fish rule-of-thumb
that allows for weekly maintenance. If you tried to convince
them to go for 20G/fish, they'd assume you were a quack and
ignore your advice entirely.

I'm pretty sure that the writer I quoted (from Aquarium USA 2004 BG)
was an experienced tropical fish keeper but not necessarily a
goldfish enthusiast. His "20-30 gallons/goldfish" rule probably
reflects that he found goldfish MUCH harder to care for than
tropicals. It took that much water in order to get to his
personal EQ (Effort Quotient).

I'm in the middle, but leaning his way myself. For
quite a while this Spring I had 4 fish in a 55G, and
two in an 18G. I was recently forced to move a fish
from the small to the large tank, and I noticed the
difference within a week -- the 18 is running much
cleaner now with only one fish, whereas the 55 now
gets noticably dirty faster than before. That shouldn't
be a surprise: the small one's load was cut by 50%
while the large one went up by 25%. When you think
of it that way, it's pretty obvious what effect the
gallons/fish metric has.

Good gravy, somebody tell me to put a sock in it!
Gunther