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This might help me explain in more detail about the difference between the two tanks.

Here are the basics
Both tanks hold same amount of water.
Same filtration, and aeration.
Same type and depth of substrate, but long has more greater base area.
Same plant but long has more as it has more base area.
Same fish how many ????

Seeing both are as equal as possible well that is impossible reason of base squarage.

Here is my question as the tall has less base squarage and less water surface area does this mean you "MUST" have less fish in the tall tank than the long tank?

Keith

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Generally, the surface area determines how much gas exchange can take place, and therefore how much oxygen can enter the water. The larger the surface area, the greater the exchange capacity.

Since fishes consume oxygen during respiration, this places an upper limit on carrying capacity (neglecting other factors of course). If one calculates the carrying capacity simply on the basis of the respiration rates of the fishes, then a tall aquarium, with lower surface area available for gas exchange, has a lower carrying capacity with respect to respiratory loading than a long, shallow aquarium of the same total volume.

Of course, for some fishes, depth is important (e.g., Angelfish, Discus) which means that this has to be taken into account when planning to house these fishes. But then one would be looking at a fairly capacious aquarium to do justice to Angelfish in any case, and CERTAINLY would be looking at a large aquarium just for maintenance in the case of Discus, let alone breeding.

Basically, a 24" long x 24" deep x 12" wide aquarium will only have half the surface area of an aquarium that is 48" long x 12" deep x 12" wide. Therefore the respiratory carrying capacity of the tall aquarium will be half that of the long aquarium. Which is why one reason long, shallow aquaria are generally preferred, apart from the fact that they tend to be more aesthetically pleasing to the eye and also provide a better 'river simulation' for fishes that originate from rivers (which are basically long and narrow stretches of water when compared to lakes).


Panda Catfish fan and keeper/breeder since Christmas 2002

Well, there's nothing that you "must" do in fishkeeping. However, there are things that are a really really really really good idea to do and things that are a really really really really good idea to NOT do.

With proper aeration, I don't think it's necessarily a gas-exchange problem, especially if you get one of those airstones that make very tiny bubbles. It's more of a configuration problem. There aren't many fish whose primary habit of swimming is vertical -- almost all would prefer to move horizontal given the chance. Since tall tanks have less horizontal space to swim, fish would be constantly going into others' territories. Now, if you have small, really peaceful fish or just one species, it probably wouldn't be too big of an issue. However, multiple semi-aggressive species would be much more stressed in a tall vs. a long tank. The fish would, however, have a higher inherent stress value because of it. Additionally, larger fish (cichlids and the like) would have even less horizontal swimming space and be under more stress , so the maximum fish size would be smaller than in a long tank.

Another thing to consider is exactly what you said about base area. If you have same depth of substrate in both tanks, the long tank would have to have more of it, so the gravel couldn't have as much bacteria to break down waste. However, if you increase water changes, it shouldn't be too big of a deal.

Last thing to consider is a finer point which probably wouldn't have much bearing, but it is still worth mentioning. In a tall tank, less light will reach the bottom than in a long tank. This will slow down plant growth. As you mentioned, with the larger footprint, the long could support many more plants. Essentially, it would take the high tank more time to "mature" and it would never reach the planted levels in the long. More plants usually means you can stock higher.

Under normal circumstances, is there much of a difference in maximum stocking levels between long and tall tanks? Probably not, provided that you do a bit more maintenance. But, to get the same fish health and general welfare, it is a good idea to stock the high less. In short, if the space allows, just get the long tank.

correct me if I'm wrong, but isn't a tall tank is better in some situations? A 20X tank is better than a 10 gallon tank. Basically a 20X is like 2 10 gallon tanks stacked on top of each other. With having the 20X, you can have more water for the fish, so if it had about the same stocking as a 10 gallon tank, the water would be more "clean" right? Also it would give the fish more swimming space, the horizontal swim space remains the same, but now they also have more vertical swim space. Also it will help for keeping bottom feeder fish from having less contact with mid level fish. However with the tank being taller, there will be less light for plants, but if you have a powerful light such as coralife brand for example, it isn't a problem then and so then taller plants can be placed in the tank.

In that situation, yes, the tank would probably be better just because of the larger water volume. Given Keith's parameters, though, the long is best.

This excellent and useful information was not for me but members who have tall tanks and think they can do exactly the same as a long tank. I have seen 6ft circular tall tank about 18ins or less in diameter and being told it was the same as a 6ft long.
Thank you to those who contributed.

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Keith

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