The "one inch per gallon" rule

BushFishRox

Jack Dempsey
MFK Member
Jul 7, 2007
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Bderick67;1105086; said:
12 adult oscars in a 180gallon tank:WHOA: not a chance

Bushfish has it right. The OP was talking area so everything would be in sq.



No because then a 12" oscar would only need an area of 144 sq" which is only one square foot, thats smaller then a ten gallon tank.

What it amounts to is the surface area equation/rule does not work. While the modified "one inch per gallon" rule does work for most fish.
other wise people would be yelling at me for making their house to small and I would be poor not rich.... I love rich people they make me rich!!! :D :ROFL:
 

shinypenny

Feeder Fish
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May 30, 2007
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BushFishRox;1105044; said:
12"sq is equal to 12"x12" (it is a square after all)...

so for 1" of fish you will need 12"x12" of space going by your theory, so if you go by that it would be 12" of fish x 12"sq of water to equal 12' by 1'(12") of water for a 12" fish... thats 6 square feet for a 6" fish...

so really I dont know what you think a square inch is...

since 1 square ft is needed for 1" of fish you take the length of the fish say 6" multiply that by 12" that would be your length and then your width would be 12" or 1' so that would be 6'x1'...
Hi again,

The original poster meant 12 square inches which is an area with dimensions 12"x1" or 3"x4" or 6"x2" for each inch of fish. 12 inches^2 is not a square foot. It is 12 x 1 inch^2.

And the word "squared" does not necesarily mean it is a square as you implied. It is purely a measurement of area, and does not imply that the area is square in shape.

Come on guys, this is elementary school math....

And the rule does not work well when used to size a tank for an oscar, just as the unmodified 1 inch per gallon rule does not work well. However modify it to allow for fish volume (as guppy did with the gallon rule, and I alluded to in my first post) and it does give reasonable estimates.

And neither rule takes into account how agressive fish are, so both are highly susceptible to errors when considering agressive species.
 

crashinc25

Feeder Fish
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Jun 27, 2007
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I can't figure where this got complicated. L x W x H = Total 3 dimensional size of a fish. If that fits into your tank, get the fish. I sat down the other night and did this with my African tank. Worked out to 89" in a 100g tank. Perfecto.
 

Bderick67

Bronze Tier VIP
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Aug 18, 2006
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shinypenny;1106474; said:
Hi again,

The original poster meant 12 square inches which is an area with dimensions 12"x1" or 3"x4" or 6"x2" for each inch of fish. 12 inches^2 is not a square foot. It is 12 x 1 inch^2.

And the word "squared" does not necesarily mean it is a square as you implied. It is purely a measurement of area, and does not imply that the area is square in shape.

Come on guys, this is elementary school math....

And the rule does not work well when used to size a tank for an oscar, just as the unmodified 1 inch per gallon rule does not work well. However modify it to allow for fish volume (as guppy did with the gallon rule, and I alluded to in my first post) and it does give reasonable estimates.

And neither rule takes into account how agressive fish are, so both are highly susceptible to errors when considering agressive species.

:screwy:
You really have no idea do you? The formula as you explain it does does not work. A single neon needs more then a 3" x 4" area to swim in. A 6" jack dempsey needs more then a 6" x 12" area to swim and we already know about the oscar. With Bushfish explanation at least fish have room to swim, but way more then needed though, so neither interpitation works. This thread is meant as a guide for beginning fish keepers and to sit and argue this is only going to add to any confusion that the beginner already has.

The modified one inch per gallon rule works. The surface area per fish does not.
 

BushFishRox

Jack Dempsey
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Jul 7, 2007
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Bderick67;1107597; said:
:screwy:
You really have no idea do you? The formula as you explain it does does not work. A single neon needs more then a 3" x 4" area to swim in. A 6" jack dempsey needs more then a 6" x 12" area to swim and we already know about the oscar. With Bushfish explanation at least fish have room to swim, but way more then needed though, so neither interpitation works. This thread is meant as a guide for beginning fish keepers and to sit and argue this is only going to add to any confusion that the beginner already has.

The modified one inch per gallon rule works. The surface area per fish does not.
exactly!!!

and if you are going to use that formula use the over exaggerated formula...:grinno:
 

jmitchell

Feeder Fish
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Apr 28, 2007
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Massachusetts
I think regardless of the situation, the flaw with all these formulas is, for example, having one dempsey in 6''x12'' of swimming space is obviously not gonna work. Either way, if everyone thinks about what theyre buying, researches, and makes sure they really want (and can accomadate) the fish they want, it will be ok. Besides, if you want tons of different kinds of fish, just do a community. I have a 7 inch tiger plec, a 6 inch spotted pike characin, and a 11 inch senegaulus (sp?) bichir in my 75, and theyre anabsolute joy to watch if you truly appreciate the beauty of each fish. Not knocking anyone, just puttin in my $.02!

-LJ
 

guppy

Small Squiggly Thing
Original poster
Apr 15, 2005
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jmitchell;1109849; said:
I think regardless of the situation, the flaw with all these formulas is, for example, having one dempsey in 6''x12'' of swimming space is obviously not gonna work. Either way, if everyone thinks about what theyre buying, researches, and makes sure they really want (and can accomadate) the fish they want, it will be ok. Besides, if you want tons of different kinds of fish, just do a community. I have a 7 inch tiger plec, a 6 inch spotted pike characin, and a 11 inch senegaulus (sp?) bichir in my 75, and theyre anabsolute joy to watch if you truly appreciate the beauty of each fish. Not knocking anyone, just puttin in my $.02!

-LJ
Jack dempsey? They get 10"x4"x1 1/2" as adult, ergo 60gallon
 

shinypenny

Feeder Fish
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May 30, 2007
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guppy;1115978; said:
Jack dempsey? They get 10"x4"x1 1/2" as adult, ergo 60gallon
and by the other rule we have 12x10x4x1.5 = 720 square inches

or a surface area of 48"x15"

which gives a standard a 55gallon tank (48x15x18)

So as I was saying the results when using the two methods correctly are aproximatly the same.
 

guppy

Small Squiggly Thing
Original poster
Apr 15, 2005
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And, as always, these "rules" are only rough guidelines, and must be adjusted for the species concerned,
for example, active, cold water fish such as trout should be allowed almost twice as much room.
 

chimbakka

Feeder Fish
Sep 10, 2007
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Kitchener, ON
shinypenny;1104939; said:
Anyone else hear of interesting rules for deciding how many fish a tank can comfortably handle?
My boyfriend has an excellent method. I keep adding fish until he says "holy **** that's a lot of fish" then I'm done. LOL
I just keep an eye on the parameters as well as how often I have to do water changes and how dirty the water is... I recently took 5 fish back to my lfs because of this, and now my tank is doing very well and is clean. My tank is all barbs, so they like a group and swim together. With fish that need space I'd use less fish/gal.
 
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