The "one inch per gallon" rule

BushFishRox

Jack Dempsey
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snakehead121;1098584; said:
cool guppy, I have used a diffrent method befor. First you find the serface area (length by width). Then for your fish for tropical freshwater 12in. per 1in. of fish, for cold freshwater 28in.(I think it may be 20), and for saltwater 48in. And for fish that go to the serface to breath double the in. requierd.
so for a 12" fish you would have 12' or 144" of space for that one fish? so that would be like 6x2 (180galish) for 1 12" tropical fish?
 

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BushFishRox;1102605; said:
so for a 12" fish you would have 12' or 144" of space for that one fish? so that would be like 6x2 (180galish) for 1 12" tropical fish?
That seems completely acceptable. So in a 180 gallon tank you could have one adult oscar, or better yet 12 neon tetras:grinno:
 

BushFishRox

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Bderick67;1102632; said:
That seems completely acceptable. So in a 180 gallon tank you could have one adult oscar, or better yet 12 neon tetras:grinno:
sure it is like having one guppy in a 55...

but it seems like a waste of space to me...
 

BushFishRox

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oh and that is for tropical fish, Cold FW and Salt need even more space for fish... seem a little to extreme for me...
 

esse

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oh ya, this is why I log in every day. :headbang2 The one inch rule is what I used in 1972, and I did not even know what it ment:screwy:
 

shinypenny

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BushFishRox;1102605; said:
so for a 12" fish you would have 12' or 144" of space for that one fish? so that would be like 6x2 (180galish) for 1 12" tropical fish?
um, I'm not sure if it's your math that got messed up, but my interpretation is that you need 12 sq inches of surface area for one inch of fish. So that 12" fish needs only 1/12 of that 6x2 tank. Or said another way that tank could hold 12 x 12" oscars, or 6x24" gars.

It is also interesting to combine the two methods (guppy's fish volume with the surface are method). I mean that would be more reasonable than just length. Although the math is a little taxing to be doing in your head when down at the lfs.

Personaly I think the surface area calculation is good for newbies to ensure that they don't crowd the tank and suffocate the fish, and the volume calculation is more useful for those of us who are looking to keep more delicate fish which require us to keep a tight control over the build up of Nitrates etc. which has more to do with volume than surface area.

BTW, how many of us truly know the volume of our tanks? I mean I own a 65 gallon, I could easily have displaced 5 - 10 gallons with decor, added 25 - 35 gallons with the sump, so altogether somewhere between 85 and 110 gallons ... it's a pretty inexact science for most of us.

Anyone else hear of interesting rules for deciding how many fish a tank can comfortably handle?
 

BushFishRox

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snakehead121;1098584; said:
First you find the serface area (length by width). Then for your fish for tropical freshwater 12in. per 1in. of fish, for cold freshwater 28in.(I think it may be 20), and for saltwater 48in. And for fish that go to the serface to breath double the in. requierd.
shinypenny;1104939; said:
um, I'm not sure if it's your math that got messed up, but my interpretation is that you need 12 sq inches of surface area for one inch of fish. So that 12" fish needs only 1/12 of that 6x2 tank. Or said another way that tank could hold 12 x 12" oscars, or 6x24" gars.
12" of water times 12" of fish is 144" or 12ft so I just folded that in half rather then say you need a 12'x1' tank...

or do you really mean 1" of fish per 1"sq of water? since you say a 12" fish would need 1/12 of a 12sq ft tank? because the way you word it means that a 12" fish needs 1sq ft of water...
 

shinypenny

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BushFishRox;1104955; said:
12" of water times 12" of fish is 144" or 12ft so I just folded that in half rather then say you need a 12'x1' tank...

or do you really mean 1" of fish per 1Gal of water? since you say a 12" fish would need 1/12 of a 12sq ft tank? because the way you word it means that a 12" fish needs a 1sq ft of water...
144" is 12"x12" so it is 1 square foot. so it would be 12 feet x 1 inch rather than 12 feet by one foot. This is because 12 feet is 144 inches.

I think the original poster meant that you need 12 square inches of surface area per inch of fish. Not 12 inches by 12 inches!

Sorry, I know I'm having trouble explaining this clearly. Does that kinda make sense? I heard this rule when I was younger so it kinda makes sense to me.
 

BushFishRox

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shinypenny;1104983; said:
144" is 12"x12" so it is 1 square foot. so it would be 12 feet x 1 inch rather than 12 feet by one foot. This is because 12 feet is 144 inches.

I think the original poster meant that you need 12 square inches of surface area per inch of fish. Not 12 inches by 12 inches!

Sorry, I know I'm having trouble explaining this clearly. Does that kinda make sense? I heard this rule when I was younger so it kinda makes sense to me.
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'...
 

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shinypenny;1104939; said:
um, I'm not sure if it's your math that got messed up, but my interpretation is that you need 12 sq inches of surface area for one inch of fish. So that 12" fish needs only 1/12 of that 6x2 tank. Or said another way that tank could hold 12 x 12" oscars, or 6x24" gars.
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.

shinypenny;1104983; said:
144" is 12"x12" so it is 1 square foot. so it would be 12 feet x 1 inch rather than 12 feet by one foot. This is because 12 feet is 144 inches.

I think the original poster meant that you need 12 square inches of surface area per inch of fish. Not 12 inches by 12 inches!

Sorry, I know I'm having trouble explaining this clearly. Does that kinda make sense? I heard this rule when I was younger so it kinda makes sense to me.
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.
 
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