Is this true?

[FrAnK3333]

i was reading and it says that the larger the footprint the more fish the tank can hold. is this true? because i have a 20 long and it exactly like a 29 gallon minus 6 inches off the height.

 

[sylvia]

Umm yes and no... you see 29 gallon tanks have the same footprint as a 20 gallon is more the way to put it - not a 20 gallon has the footprint of a 29 if you get me... So simply put, you can't keep more in your 20 gallon just cause 29's are made to just be taller than 20's Surface area is a good way to calculate stocking levels but is only accurate when used in conjunction with gallonage - you couldn't keep a pleco in a 40 gallon if it just happened to be lower and longer... On the other hand, a long low 10 gallon COULD hold more bottom-dwelling small fish (such as shell-dwelling cichlids) than a tall one but yeah - you have to consider gallonage and use common sense and watch your nitrAtes.

 

[blue_ram]

i was reading and it says that the larger the footprint the more fish the tank can hold. is this true? because i have a 20 long and it exactly like a 29 gallon minus 6 inches off the height.

Actually 20g long won't hold any more fish than the standard 20g. But it will hold larger fish than the regular 20g.
There are two rules that apply; your standard inch/gallon rule and the swiming space rule. The swiming space rule is mine.

The swiming space rule is determined by the surface area, and is used to determine the largest fish that the tank can accomodate. Since the footprint of the 20L is the same as 29, you can keep a fish that would normally be a tad too large for standard 20g.

But your stocking density rule of inch/gallon still applies, as it's used to determine the bio-load bearing capability of the aquarium. So for stocking rule purpose, gallon is a gallon; regardless of the containing dimension.

As a simple example, assume you have a 90g (XXX tall) aquarium with the same footprint as the 29g . Normally, a 90g will easily accomodate a single 12 inch oscar. But due to the footprint, you're restricted to the fish that can be kept in 29g. But you can keep 3 times the number of fish as the 29g.

 

[freddyk]

But your stocking density rule of inch/gallon still applies, as it's used to determine the bio-load bearing capability of the aquarium. So for stocking rule purpose, gallon is a gallon; regardless of the containing dimension.

We, there is room for more fish in a long tank, and power filters can handle the bio-load. The question when it comes to stocking levels is more about how the aquarist can handle the extra maintenance of the tank that higher stocking levels require.

 

[sylvia]

I have always considered the surface area a determining factor not because of swimming space, bio-load or maintainance but because it allows for less oxygen to enter the water. Thus, it can hold less fish. That (and not bio-load or whatever) is why a 20 gallon tall can't hold as many fish as the twenty gallon long. Obviously, swimming space does play a part - like you shouldn't keep a zebra danio in a tall tank - but with many species it is the oxygen that makes the difference in tall tanks and volume is what usualy determines the size of fish (as well as the tank's dimensions.
What I mean to say is that you could have a bottle-shaped 500 gallon tank filled to the rim but you couldn't keep more than a few guppies because the amount of oxygen that could enter through the tiny surface area allowed by the bottle's narrow neck would not make it possible for enough oxygen to enter the water for a couple of full-grown common plecs, some bala sharks and a group of clown loaches (or whatever you'd put in that sort of tank). Though, boviously, the 'body' of the tank would be able to accomodate them as regards to swimming space and volume.
I've got it with a little re-phrasing... It's the surface area to volume ratio that matters.