Zëbulon wrote in
:


"nut" wrote in message
...
Zëbulon wrote:
"Tynk" wrote in message
oups.com...
You cannot set such a vague "rule" when there are way too many
variables when it comes to stocking a fish...much more than it's
size in inches.
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Such as the fact a 1" goldfish passes a lot more waste than a 1"
guppy.

The rule was for tropical fish, not coldwater.
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This is true but how many newbies know that? They come here all the
time asking about putting tropicals with goldfish. Some people keep
them together successfully.

Also, some tropicals have a lot more bulk per inch than others.

It would be good to have something a little more accurate than the inch
per gallon guide. In one article I read, they made the excellent
suggestion that the "real" main limiting factors for an aquarium are
mass of fish as adults vs. water surface area of the tank (which is a
more measurable equivalent to oxygen transfer rate), with different
stocking ratios for Fresh, brackish, salt, (and warm and cold) waters.

You could further modify this by multiplier factors considering things
like whether additional oxygenation/waste management is available
(airstone, planted tank etc), or fractional multipliers for if you're
keeping only carnivorous fish (more waste). The main advantage is that
you get a better feel for the differences in body types. The drawback
is that I haven't found many sources which report average/typical adult
fish mass. This is one of them;

http://www.aquariumfish.com/aquarium...aid=323&cid=53
&search

For common freshwater species, that table gives you neons at 0.2g and
7cm discus at 19 g. If anyone knows of other resources which report
more adult typical mass values for FW aquarium species, I'd love to see
it. I could bring my fish into work, and weigh each immersed in a fixed
volume in a graduated cylinder (and then weigh the water afterwards to
calculate their mass), but I'd rather save them the stress of such a
trip.

Even after all that, metabolic rate doesn't scale directly with mass of
the fish, but this would be a step in a more accurate direction.

DaveZ
Atom Weaver